Add XTest input fallback

[Doridian]

Description

This includes a way for Sunshine to utilize XTest for inputs in the event libev/uinput is unavailable (such as inside an un-privileged Docker container)

Let me know how this looks code-wise. Likely the direct calling of X functions needs to be changed, considering you seem to use the dyn::load semantics elsewhere. Done

This also removes the useless pressed integer (grabbing the value out of the array creates a copy, so pressed was never actually anything but 0)

It also removes the loops in init_keycodes, most of which were useless (as they were all explicitly mentioned via __CONVERT), and replaces them with full explicit key constants.

Screenshot

Issues Fixed or Closed

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

Branch Updates

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must be updated before it can be merged. You must also
Allow edits from maintainers.

• I want maintainers to keep my branch updated

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[ReenigneArcher]

Are you on our discord server so we can discuss this in real time?

[Doridian]

@ReenigneArcher Just joined, same name as on GitHub.