add ItemFrameMeta API

[TehBrian]

Draft PR; CraftMetaItemFrame is (probably) currently non-functional, but I wanted to share progress so far.

The second commit is a rewrite based on #11107, and I'm waiting on that PR to finalize changes here.

Concerns:

• Do we have to care about entity ID being different for glow item frames? Does that warrant a separate GlowItemFrameMeta? Entity IDs only even seem to matter on spawn eggs.
• Should CraftMetaItemFrame be wrapped in // Paper? It's in org.bukkit (because there were a nightmarish amount of access transformers until I moved it from io.papermc), but it's also a new file.

Please let me know your thoughts :D

[github-actions]

Please do not open pull requests from the master branch, create a new branch instead.

[TehBrian]

oopsie :3