Svelte: Create consistent, predictable, intuitive keyboard shortcuts

[taiyab]

As we progress through our implementation of the new file view designs, we're starting to surface the keyboard shortcuts used to trigger various actions on the UI.

For example:

• / triggers global finder/search
• ⌥R might trigger revision selector
• ⌥N might trigger opening a new file pane

etc. etc.

We need to establish a set of shortcuts that make sense system-wide, and match up to other common shortcuts used in other systems and tools/IDEs.

We also need a way to universally show these keyboard shortcuts and hence a binding to show and hide that panel too (which preferably corresponds to the "prefix" we use, e.g. in the cases above, ⌥, so hitting ⌥ might bring up the keyboard shortcuts available to you in a menu).

The work here would be to:

• Gather all the places throughout the system that we'd want to enable a shortcut for
• Ensure a consistent pattern of shortcuts throughout
• Ensure no overlap in shortcuts used
• Ensure the shortcut mapping is intuitive
• Ensure the mapping works across all operating systems
• Create a better way for us to assign and manage these keyboard shortcuts, all in one place

Anything I've missed here? @camdencheek @vovakulikov @fkling