RPCv08rc-0 methods

[rianhughes]

https://github.com/starkware-libs/starknet-specs/tree/v0.8.0-rc0

New websocket methods

• [ ] starknet_subscribeNewHeads
• [ ] starknet_subscribeEvents
• [ ] starknet_subscribeTransactionStatus
• [ ] starknet_subscribePendingTransactions
• [ ] starknet_unsubscribe

Other new methods

• [ ] starknet_getMessagesStatus
• [ ] starknet_getStorageProof
• [x] starknet_getCompiledCasm

Other changes

• [ ] Error changes: CONTRACT_ERROR, TRANSACTION_EXECUTION_ERROR, INSUFFICIENT_RESOURCES_FOR_VALIDATE
• [ ] Block header now contains l2_gas
• [ ] Fee_estimate changes
• [ ] Execution_resources changes + remove computation resources (https://github.com/starkware-libs/starknet-specs/pull/216/files)
• [ ] getTransactionStatus now returns failure_reason
• [x] Event field can be flat
• [x] Remove existing 0.6 endpoints

Wallet API methods I don't think these are relevant for Juno.