Add command bar for common Spectacle operations

[carloskelly13]

Description

Add a command bar to Spectacle that can quickly let users perform the following commands:

• Enter/Exit Presentation Mode
• Enter/Exit Overview Mode
• Enter Export Mode (and preferably launch the browser dialog to export to PDF)
• Next Slide
• Previous Slide
• Restart Presentation
• Start/Restart Timer (if in Presenter mode)
• Pause Timer (if in Presenter mode)

Proposal

Investigate if KBar is the best solution for a React-based command bar.

Links / References

KBar React Library

[mwritter]

Kbar has a couple of dependencies that don't support our current version of 'react' and 'react-dom' - in the examples

@carlos-kelly - other than these peer dependency issues kbar seems to work fine in the example projects.

[mwritter]

@carlos-kelly @gksander - quick mvp:

Screen.Recording.2022-07-21.at.10.16.17.AM.mov

The 'command bar' works as expected, keyboard shortcuts also trigger the appropriate 'actions'.