Improve mouse and keyboard UX

[somebody1234]

Pull Request Description

• Close https://github.com/enso-org/cloud-v2/issues/914
  • Add selection brush for selecting multiple assets using mouse
    • Port selection brush over from GUI2
    • Support Ctrl-select to select multiple ranges
  • Add various actions when exactly one asset is selected:
    • Enter for various assets to trigger their double-click actions
      • Projects are opened
      • Directories are toggled open/closed
      • Secrets show the "upsert secret modal"
    • ArrowLeft now collapses the selected folder
    • ArrowRight now expands the selected folder
    • ArrowUp and ArrowDown change the selected asset to the previous/next asset
      • The newly selected asset (technically: any asset that is the only selected asset, whether this is a result of a drag, mouse click, or keypress) is automatically smoothly scrolled to.
  • Improvements to the search bar
    • Escape cancels tabbing through suggestions (and discards the selected suggestion)
    • ArrowUp and ArrowDown behave like Shift+Tab and Tab to move to the previous/next suggestion respectively
  • Shift+ArrowUp and Shift+ArrowDown to select multiple assets using the keyboard
  • Ctrl+Space to toggle assets using the keyboard
  • Escape to deselect all assets
  • Add CSS-only focus ring to highlight most recently selected item, but only when navigating via keyboard
  • Enter and double-click to temporarily open the sidebar to edit a Data Link

Optional features that have not yet been implemented:

• Move the "update secret" modal to the sidebar as well

Important Notes

None

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
  Java,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• All code has been tested:
  • Unit tests have been written where possible.
  • If GUI codebase was changed, the GUI was tested when built using ./run ide build.

[PabloBuchu]

| Ctrl+Space to toggle assets using the keyboard

this seems to have no effect on mac. cmd + space opens system spotlight search maybe this is why

[somebody1234]

makes sense. we should probably just copy macOS' equivalent shortcut to Ctrl+Space?

[PabloBuchu]

Apart from above and merge conflitcs looks good. Lemme know if we want to fix this in separate PR or not

[somebody1234]

yeah, probably doesn't make sense to block this PR