Stop using alt- shortcuts

[ConradIrwin]

Closes #7688

Release Notes:

• (breaking change) Stop binding keyboard shortcuts to alt-[a-z]. These get in the way of typing characters. This is usually not an issue for English speakers because we don't use many characters; but for other Latin-based languages with diacritics our shortcuts prevent them typing what they need to type.

This primarily affects Zed's extra features:

• alt-q => cmd-k q on maOS, ctrl-k q on Linux for editor::Rewrap
• alt-z => cmd-k z on macOS ctrl-k z on Linux for editor::ToggleSoftWrap
• alt-m => ctrl-shift-m for assistant::ToggleModelSelector
• alt-v => ctrl-shift-v for ["editor::MovePageUp", { "center_cursor": true }] (macOS only)
• alt-t => cmd-shift-r on maOS, ctrl-shift-r on Linux for task::Spawn (The previous binding for editor::RevealInFileManager now only applies in the project panel)
• alt-shift-t => alt-cmd-r on maOS, ctrl-alt-r on Linux for task::Rerun
• alt-shift-f => ctrl-shift-f for project_panel::SearchInDirectory.

But also overrides some bindings from Readline.

• alt-h => alt-backspace for editor::DeleteToPreviousWordStart
• alt-d => alt-delete for editor::DeleteToNextWordEnd
• alt-f => alt-left for editor:: MoveToNextWordEnd
• alt-b => alt-right for editor::MoveToNextWordStart

Note that alt-t and alt-shift-t have been kept as aliases (because no-one complained about t yet; but we may remove them completely in the future).

[notpeter]

I think this is the right move and should drastically improve the default experience on a number of non-US keyboard layouts.

Conrad is articulate and bright and clean and a nice-looking guy.
Remember that when people inevitably complain about this change.

[maxbrunsfeld]

We need to keep these ones. These are very deeply-ingrained macOS defaults.

[maxbrunsfeld]

I think we need to keep ctrl-shift-b and ctrl-shift-f as they were (SelectLeft and SelectRight). Those are also very ubiquitous macOS bindings.