Adding candy_guard parser

[danenbm]

Notes

• Builds on Adding candy_machine_core parser #5
• Also related to: Expose MintCounter and do some cargo fmt/clippy fixes mpl-candy-guard#25 (points to that branch).
• Parses CandyGuard struct as well as default and optional guards.
• Also parses MintCounter PDA.

[febo]

All good with the implementation, below are some aspects that we might need to think about:

1. There is a MintCounter PDA per wallet, which in turn can exist in multiple groups (GuardSets); therefore, we will probably have thousands of PDAs per Candy Guard account. It would be interesting to index those since any UI will need to fetch the PDA to check whether a wallet can mint or not, otherwise the guard validation could fail and the wallet charged a bot tax.
2. It is very likely that future guards incorporate other PDAs, so it is possible that PDAs will exist before the parser code gets updated. Perhaps we need a good way to handle unrecognized accounts in the parser – some sort of categorization that a new PDA is being used.

[austbot]

@febo the parser gets all current accounts flushed at it during startup, but you are right unless we know the structure of thoise pdas we will have to just store rraw bytes. I think we have to be diligent to get parser code out before major updates to core programs, in this case we can store all accounts from candy guard and reup later