[Key handling] pass through all keys; allow specifying modifiers for validKeys[Down|Up]

[nakambo]

There are scenarios where it might be necessary to look at the incoming events without removing from the system queue. Currently that's impossible today on React Native macOS, since views are required to specify validKeysDown or validKeysUp, and such events are always removed from the queue.

To mitigate, let's add a new passthroughAllKeyEvents prop to RCTView. We could keep it forever (towards an interest to reduce event spam from native to JS), or we could use it towards the path to making it the default behavior (stage 1: default false, i.e. opt in, stage 2: default true, i.e. opt out, stage 3: remove, is default behavior).

• React/Views/RCTView.h
• React/Views/RCTView.m
• React/Views/RCTViewManager.m

Note that this doesn't properly work with RCTUITextField (i.e. single line text fields). From what I can tell, that would need us to possibly provide a custom field editor for the window (or an event monitor). I am scoping this out for this PR.

Another peculiarity to note is regarding RCTUITextView (i.e. multi line text fields). Here, it looks like the text view itself isn't exposed to the JS (this view doesn't have a nativeTag), so there's a RCTView holding a child RCTUITextView where the former dispatches events to JS on behalf for the latter. The reason this matters (specifically for "pass through" events) is because the latter can dispatch certain events to the JS, and then depending on the super class implementation (NSTextView), it may or may not also pass the NSEvent to the next responder (i.e. parent view, i.e. RCTView). Passing the action to the next responder can cause us to send duplicate JS events for the same NSEvent. I couldn't find anything in macOS APIs to determine if the view the event was generated for is a specific view, so I am introducing a book-keeping mechanism to not send duplicate events.

Also note that on the web, it looks like input events generated by input controls (and the like) bubble to parent elements even when "handled" (as in, inserted into the text input). Given how things are currently implemented (direct events originated from NSResponder selectors), once an event is "handled" (e.g. inserted into a NSTextView), it stops propagating along the responder chain, meaning we don't simulate the web behavior (e.g. even if a parent React view opts into all keyboard events)

Introduce RCTHandledKey for specifying modifiers for validKeysDown and validKeysUp. Behavior noted in type definitions.

• Libraries/Text/TextInput/RCTBaseTextInputView.m
• React/Base/RCTConvert.h
• React/Base/RCTConvert.m
• React/Views/RCTHandledKey.h
• React/Views/RCTHandledKey.m
• React/Views/RCTView.h
• React/Views/RCTView.m
• React/Views/RCTViewKeyboardEvent.m
• React/Views/RCTViewManager.m
• React/Views/ScrollView/RCTScrollView.m

macOS usually does things on key down (as opposed to, say, Win32, which seems to usually does things on key up). Like RCTUITextField, passs performKeyEquivalent: to textInputDelegate so we can handle the alternate keyDown: path (e.g. Cmd+A). This will be needed for properly handling keystrokes that go through said alternate path. There are probably several other selectors that also need implementing (deleteBackward:) to full pass through every possible key, but I am leaving that for some other time.

• Libraries/Text/TextInput/Multiline/RCTUITextView.m

Make a totally unrelated fix to RCTSwitch. In a test page where I added an on-by-default switch, I noticed the first toggle (ON->OFF) doesn't do anything. The second toggle (OFF->ON) then doesn't (expectedly) do anything. Found wrong behavior on the switch test page -- tempted to instead remove wasOn, but for now repeating the pattern in setOn:animated:

• React/Views/RCTSwitch.m

This demonstrates the wrong\before behavior:

• https://github.com/microsoft/react-native-macos/assets/72474613/2a7cff6a-663d-4c26-bfac-2547a720b125
• https://github.com/microsoft/react-native-macos/assets/72474613/927bb840-352d-498d-9ea9-7455140ed9fd

Flow stuff. passthroughAllKeyEvents is now a valid thing to pass to View types.

• Libraries/Components/View/ReactNativeViewAttributes.js
• Libraries/Components/View/ViewPropTypes.js
• Libraries/NativeComponent/BaseViewConfig.macos.js

Update signatures for validKeysDown and validKeysUp

• Libraries/Components/View/ViewPropTypes.js

Remove duplicated specifications on Pressable. Just use the one from View. As a benefit, future changes allow us to not have to touch Pressable anymore.

• Libraries/Components/Pressable/Pressable.js
• Libraries/Components/View/ViewPropTypes.js

Update test pages with passthoughAllKeyEvents and the keyboard events page with an example modifier usage.

• packages/rn-tester/js/examples/KeyboardEventsExample/KeyboardEventsExample.js
• packages/rn-tester/js/examples/TextInput/TextInputSharedExamples.js

Please select one of the following

• I am removing an existing difference between facebook/react-native and microsoft/react-native-macos 👍
• I am cherry-picking a change from Facebook's react-native into microsoft/react-native-macos 👍
• I am making a fix / change for the macOS implementation of react-native
• I am making a change required for Microsoft usage of react-native

Summary

1. Adding an API to pass through all key down and key up events
2. Modifying validKeysDown and validKeysUp to allow specifying modifiers
3. Bug fix for on-by-default switch

Changelog

• [General] [Added] Initial version

Test plan

• Using the keyboard events test page, validate "pass through" of all events for simple view, single line text input, multi line text input. Sanity test existing (non-"pass through") behavior.
• Using the text input test page, ordering of keyDown and keyUp events w.r.t. other events (such as keyPress -- which isn't dispatched for every key)
• Using the switch test page, sanity test switch behaviors

[Saadnajmi]

Left some comments and asks for changes.

Also, Some links that might be helpful for both of us as reference

RCTUITextView implementation details (aka, why it's a child of a normal RCTUIView)

• Support arbitrary selectable text in Text component #1346
• Only forward click events to NSTextview #1515

Getting TextInput to support onKeyDown/validKeysDown (and vice versa), both single and multi-line:

• https://github.com/microsoft/react-native-macos/pull/1345/files

[Saadnajmi]

Overall looks good, I left a few nits here and there. I'm going to do an A/B test of RNM with and without this change to compare behavior to ensure we aren't breaking :)

[Saadnajmi]

Minus some missing diff tags, LGTM!