implement ChainInterface for Solana

[Sladuca]

Basically what the title says. This would be better to do sooner rather than later because then we can move the account-mapper contract to Solana, which is probably the better L1 to use for a "quick lookup" since every account could have a separate map for linking together all of the accounts, which is probably better than having a single global state mapping together every chain's account for every user of BAF wallet.

Before this issue becomes actionable, a bit of scoping is probably necessary in order to figure out how we're going to deal with the fact that you need to manually de-serialize the account state after you fetch it from chain, as solana accounts are merely buffers equipped with pubkeys and balances.