[token-2022] Remaining tasks for the confidential transfer extension

[samkim-crypto]

Adding a list of remaining TODOs for the confidential transfer and confidential transfer with fee extension programs.

Confidential Transfer

• Update confidential transfer Transfer and TransferWithFee instructions for the Solana 1.16 updates
  • [token-2022] Update confidential transfer Transfer and TransferWithFee for Solana 1.16 #4779
• Add support for context states (not split)
  • [token-2022] Add support for context state accounts #4816
• Add support for context states (split)

Confidential Transfer with Fee

• Divide the withheld amount in an account into lo and hi parts
  • Currently, the encrypted withheld amounts is encrypted as a full number. To ease decryption, this amount should be split into lo and hi parts like in the pending balance of the confidential transfer extension.
• Update the WithdrawWithheldTokensFromMint and WithdrawWithheldTokensFromAccounts instructions for the Solana 1.16 updates ([token-2022] Update confidential transfer fee extension for solana 1.16 #4896)
• Add support for context states (not split)
• Add support for context states (split)