Add ability to edit keyboard shortcuts (hotkeys)

[franknoirot]

Add UI and system to view and edit keyboard shortcuts (or hotkeys). Related to and extends #504. This UI will be added to the settings modal as a tab that is available from the Home or within a project, and mockups can be found here. Here is the key mockup:

and here are a few UX notes:

1. Hotkeys will start respecting scopes as made available by react-hotkeys-hook
2. Hotkeys for the app will be consolidated to one location, with a config object similar to initialSettings
3. Hotkeys can be marked as editable or not by devs
4. Editable hotkeys are treated similar to settings, with modified ones being persisted and loaded from user.toml settings file under their own category.
5. Hotkeys can be marked as initially set to a value or not set by devs.
6. The hotkey context string will be a human-readable string that will also be used as the description line for the hotkey in the settings UI.
7. No hotkey-related settings will be available from the command bar for now