Accessibility: Support disabling global character keyboard shortcuts

Created by: umpox

Description

As part of WCAG 2.1, we need to provide a mechanism to remap or turn off character key shortcuts.

This PR:

• Makes it possible to disable our global character key shortcuts
• Refactors our shortcuts to use a useKeyboardShortcut hook so we no longer:
  • Pass keyboardShortcuts down as props in lots of places
  • Directly import and use keyboard shortcuts.

Note I noticed a few areas where we can improve our keyboard shortcuts, this is not relevant to this PR, but should be done for future work: (These are captured in this issue: https://github.com/sourcegraph/sourcegraph/issues/39218)

• We currently rely on a single set of keyboard shortcuts everywhere. This might burn us in the future (e.g. if we use a conflicting shortcut). We could modify our existing approach to pass a set of shortcuts into our ShortcutContext, this would let us vary them depending on the environment.
• We currently rely on an NPM package @slimsag/react-shortcuts that doesn't appear to have a public repository. We should bring this in-house, as it is already a fork of a Shopify package.
• We have a series of shortcuts that do not use this method for keyboard shortcuts. We should update these.

Test plan

Tested locally:

• Using keyboard shortcuts
• Disabling character key shortcuts

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.