feat: gamepad tester

[ReenigneArcher]

Description

This PR adds a gamepad tester to the LizardByte website.

TODO:

• is it possible to detect which type of gamepad is connected?
• determine how to name buttons, if we can't detect the type of gamepad then we may need to use b0, b1, etc. instead of A, B, X, Y, etc.
• shrink UI so it fits without scrolling
• improve buttons, ideas:
  • have a circular progress bar with button text inside, e.g. button name and percentage
  • have a square progress bar with the button name and percentage overlayed on top
• no hover effect on buttons

For the future:

• Add gamepad SVG images that change based on detected controller type

Screenshot

Firefox

Chrome

Original

Issues Fixed or Closed

• Closes Sunshine: integrate or document gamepad-tester roadmap#63

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Dependency update (updates to dependencies)
• Documentation update (changes to documentation)
• Repository update (changes to repository files, e.g. .github/...)

Checklist

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated the in code docstring/documentation-blocks for new or existing methods/components