Adds basic keybinding for focusing on an element in outline pane

[lambainsaan]

This PR fixes #90732.

You can test out the change with the new key binding added under the name list.focus for the same feature.

[msftclas]

All CLA requirements met.

[jrieken]

Outline changes look legit - to @bpasero for changes on the list commands

[bpasero]

This is very hard to understand until you realize that you added a list.focus command that is pretty much a copy of list.select with just a few modifications. Can you extract all the code of both commands into 1 reusable method and make the things that are actually different adjustable from the outside?

I also see that you changed from:

const fakeKeyboardEvent = getSelectionKeyboardEvent('keydown', false);

to

const fakeKeyboardEvent = getSelectionKeyboardEvent('keydown', true);

for the existing list.select. What is the reasoning?

[lambainsaan]

This is very hard to understand until you realize that you added a list.focus command that is pretty much a copy of list.select with just a few modifications. Can you extract all the code of both commands into 1 reusable method and make the things that are actually different adjustable from the outside?

Agreed, I was thinking on the same lines, but I refrained from doing it. I will update the PR.

I also see that you changed from:

const fakeKeyboardEvent = getSelectionKeyboardEvent('keydown', false);

to

const fakeKeyboardEvent = getSelectionKeyboardEvent('keydown', true);

for the existing list.select. What is the reasoning?

Oh yes, looking back at it, it does not make sense to me. It should not have changed. I will switch to the older version for this, and flip the usage.

[lambainsaan]

Left it hanging for quite sometime, @bpasero could you please take a look at it again? :)

[bpasero]

Also adding @joaomoreno to comment on the fact that we are about to introduce a new list/tree command list.focus that only differs from list.select in that it will retain focus.

I wonder if the name should actually be list.selectKeepFocus or so, because I think no-one really understands the difference between focus and select?

[joaomoreno]

As you move up/down in the outline (and any tree/list) you're moving the focus. If you press Enter, you're selecting the focused element. When things get selected, editors open. Also, it just so happens that we've made a decision to always move DOM focus away from the list/tree and into the editor when this happens. So, we need to add a new keybinding which does the same but preserves the DOM focus.

Calling it list.focus is indeed a bad name. I would call it list.selectAndPreserveFocus to match list.select.

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@bpasero The concept exists everywhere. Here's windows:

All those folders are selected, but only recipes is focused.

[bpasero]

Yeah, I like list.selectAndPreserveFocus. @lambainsaan can you make these changes?

[lambainsaan]

Sure thing, @bpasero , I have made the changes.

[bpasero]

Thanks!