Consider changing the default shortcut for accepting inline completions

[krassowski]

Problem

Currently inline completions are accepted using Alt + End.

Problems:

• this shortcut is not very convenient to use (Alt and End are far away on most keyboards)
• other applications use a different shortcut

Design constraints:

• using just End or just → is not desirable as these would interfere with the native cursor movement behaviour
• ideally there would be a natural variant of the shortcut for partial acceptance ([Inline completion] Accept completion word by word and line by line #15531); for example if the "accept all" is Ctrl+→, we could use Ctrl+Alt+→ for word-by-word acceptance (there are also line-by-line and character-by-character options)
• the shortcut should be intuitive to the users coming from other applications:
  • fish uses:
    • End or → for full acceptance
    • Alt+→ or Alt+F for word-by-word
  • IPython uses:
    • End or Ctrl+F for full acceptance
    • Alt+F for word-by-word
    • Ctrl+→ for token-by-token (word-by-word but with a better implementation)
    • Alt+→ for character-by-character
  • Copilot uses:
    • Tab for full acceptance
    • Ctrl+→ for word-by-word
• using Tab might be surprising because we use it to invoke completer
• the shortcut should ideally not interfere with any browser or OS shortcuts

Proposed Solution

Add a default shortcut other than Alt + End for accepting the inline suggestion.

Additional context

We can keep Alt + End to avoid breaking the experience of users that got used to it (we can have multiple shortcuts here).

[JasonWeill]

Using any non-alphanumeric character in a shortcut will require us to test with a variety of keyboards, including small keyboards (such as laptop keyboards) and layouts used in Europe and Asia. Not all keyboards include an End key, or require chording with a Fn key to have the effect of pressing one, for example.