Sign in with Solana

[Funkatronics]

Still needs a bit of tweaking and review, but SIWS is working!

Both fakedapp and fakewallet have been updated in this PR. Fakedapp now has a "Sign in with Solana" button that will initiate an authorize request with a sign in payload. Fakewallet has been updated with a new UI to handle authorize requests that contain a sign in payload. Fakewallet with both authorize the dapp and sign the sign in payload in one step. There is also a "Simulate Sign In Not Supported" button on this UI that will complete the authorize request and ignore the signin payload, to simulate a legacy wallet, or a wallet that does not the solana:signInWithSolana feature. In this case, Fakedapp will fall back on a generic sign message request immediately after the authorize request is completed by the wallet. In both casesfakedapp will verify the signed payload and display a success message.

completes implementation for #439

[Funkatronics]

Review notes:

This pr is quite large, but can be broken down by lib

• common
  • contains the core SIWS payload struct and message+json parsing
• walletlib
  • added the sign_in_payload to the authorize request and forwards this to the wallet for handling (if present)
  • added the sign_in_result to the authorization result so wallets can pass the signed payload back to the dapp along with the authorize request
• client lib
  • added the (optional) sign_in_payload to the authorize request input and returns the sign_in_result from the wallet

Sample apps:

• fakedapp
  • added a "Sign in with Solana" button that does authorize with a sign_in_payload
  • if the wallet fails to return the sign_in_result, it falls back on sign_message immediately after the authorize request is successfully completed
    • this could be handled in clientlib but it required significant refactor so left it here for now. clientlib-ktx could easily handle this for the consumer however (cc @creativedrewy).
• fakewallet
  • adds a new authorization fragment that specifically handles an authorize request with a sign_in_payload
    • There is also a "Simulate Sign In Not Supported" button on this UI that will complete the authorize request and ignore the signin payload, to simulate a legacy wallet, or a wallet that does not the solana:signInWithSolana feature

[creativedrewy]

A lotta plumbing for...something useful?

[creativedrewy]

The ergonomics of this object feels...odd, given its overlap with some of the values in the AuthorizedAccount object. But I don't really think there is a better option than this. I think you were forced to bolt this on.

[Funkatronics]

yeah im not thrilled with it. I could subclass the authorize objects but that would add complexity elsewhere so this felt the least bad (lol).