CreateMint instruction

[grod220]

This PR builds out the CreateMint instruction enabling the creation of "wrapped" token-2022 tokens from existing spl-token tokens (and vice versa). The intention is to facilitate interoperability between different token standards.

Mainly creates two accounts:

• Wrapped Mint Provisions a new mint account for the wrapped token. The address of this wrapped mint is deterministically derived as a PDA from the unwrapped mint address.
• Backpointer Provisions a backpointer account (PDA), derived from the wrapped mint address. This account stores a reference to the original unwrapped mint, facilitating reverse lookups.

Future work to build out remaining wrap & unwrap instructions.

[buffalojoec]

@grod220 as per discussion on Zoom, there were a few small changes you wanted to make, then I can review. Just let me know when you're ready with a comment + tag!

[grod220]

@buffalojoec Ready for your review 🙏

[buffalojoec]

Looking great so far! Nice work.

I left a bunch of comments, a lot of them small/nits, and I only skimmed the tests for now. I'll look at those closer once we've chatted about the other items!

[joncinque]

Lots of great stuff here! Mostly small things, and I agree with all of Joe's points

[joncinque]

Looking close! Mostly small things, then I'm happy to get this in

[joncinque]

Looks good to me! But do get an approval from @buffalojoec too

[buffalojoec]

Awesome! This is super close, just a few tiny nits.

[buffalojoec]

Nice! Thanks for all of the back and forth!