feat: Add global hotkey support

[sinaru]

Description

The video player does not currently support global hotkeys. Hotkeys only work when we have focus on the player. This PR is to introduce global hotkey support.

With this change, for example, if you land on the page with a video player, and does not have focus on any specific fields like form fields or the video player, you can perform a hotkey event like space bar key press which will play/pause video.

Specific Changes proposed

Global hotkeys are not turned on by default. To turn on, need to set userActions.globalHotkeys option to true. As below:

var player = videojs(vid, {
  userActions: {
    globalHotkeys: true,
    hotkeys: true
  }
});

Requirements Checklist

• Feature implemented / Bug fixed
• If necessary, more likely in a feature request than a bug fix
  • Change has been verified in an actual browser (Chrome, Firefox, IE)
  • Unit Tests updated or fixed
  • Docs/guides updated
  • Example created (starter template on JSBin)
  • Has no DOM changes which impact accessiblilty or trigger warnings (e.g. Chrome issues tab)
  • Has no changes to JSDoc which cause npm run docs:api to error
• Reviewed by Two Core Contributors

[welcome]

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[codecov]

Codecov Report

Attention: Patch coverage is 55.55556% with 4 lines in your changes missing coverage. Please review.

Project coverage is 83.23%. Comparing base (ecef37c) to head (461bab0).
Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/js/player.js	55.55%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8906      +/-   ##
==========================================
- Coverage   83.25%   83.23%   -0.02%     
==========================================
  Files         120      120              
  Lines        8097     8106       +9     
  Branches     1944     1947       +3     
==========================================
+ Hits         6741     6747       +6     
- Misses       1356     1359       +3     

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[mister-ben]

This could use some tests. Especially to cover cases where the a keypress on other elements shouldn't trigger the action.