Simple API for rendering glyphs of bindings/inputs

[xale]

Describe the feature
A simple class, e.g., InputDisplayStrings with methods like string GetButtonDisplayString(GameInput.Button)

Purpose
Since there are a number of ways across both games to render an a given button or key as a string for display to the user, a single, simple class that provides the appropriate methods would be great to have.

Usage
Rendering glyphs for inputs is useful for GUI changes and QoL features.

[xale]

I have a prototype for this, if anyone's interested in looking it over: xale@127bb87

[32Kallies]

Would this be much difference in practice from the existing method GameInput.FormatButton(GameInput.Button action, bool allBindingSets = false)?

[32Kallies]

I do notice this one accepts KeyCodes, which is nice though those are obsolete for Subnautica, but may still be used for Below Zero? I'm not actually certain on how Below Zero handles it. If this adds enough additional unique functionality it is worth considering.

[xale]

The main reasoning here is that Below Zero doesn't appear to have an equivalent to GameInput.FormatButton, and the other button-rendering functions have usage differences.

This PR would serve as a "shim" that allows mod authors to use the same API for both games, reducing the need for conditional compilation.

Support for KeyCodes was just sort of thrown in because it wasn't too hard to add.

[xale]

Ironically, someone on the SN Modding Discord just ran into a related issue:

"No, now I realise the problem. Assembly-CSharp has the method, but the publicised copy I have is from the previous version.

...wait, that just makes things more confusing. The old version had the FormatButton method, the new version has the method..."

sigh Okay, now I get it. Visual Studio decided to change to the BelowZero configuration for no reason, and apparently GameInput in BelowZero is, in fact, a MonoBehaviour."