Add LuaLS annotations

[ptdewey]

Added class definitions for Grid and Animation with their respective fields and functions.

This makes anim8 easier to work with by providing better completion and better function signatures. Signature help now displays parameter types instead of "any."

The types should be correct (or mostly correct), but please feel free to correct any mistakes. I didn't write descriptions for public function params, but those could also be added later.

Formatting note: I forgot I had stylua running automatically, so the script was reformatted. If desired I can revert to the original formatting.

Feel free to merge this PR or provide feedback. I found these updates helpful for my own work and hope they might benefit others as well.

Thanks!