[WIP] Conversion to Godot 4.2

[ephread]

Complete conversion to Godot 4.2.

It's in pretty good shape and usable, but still a work in progress because I want to take advantage of the new static properties.

Will update this PR as I go.

[mttkay]

@ephread Amazing work! Regarding the open issue:

I want to take advantage of the new static properties

Is this just an internal refactor or does it materially affect a game's integration with inkgd? If it's the former, would there be value in already merging your work to the main branch and make it the default work stream so folks can start using it in their games?

I think this would help getting more eyes on functionality and code earlier, and regressions can be found more quickly. WDYT?

I haven't personally started migrating my game to Godot 4 yet because inkgd is the primary logic driver in my game so it's a bit of a catch-22 for me.

Has anyone else already started integrating against this branch? I think @francoisdlt has already?

[francoisdlt]

Yes I have started using the godot4 branch in production. So far so good !