LABS-126 Update the wallet rpc "add_key" to support labels

[BrandtH22]

Our codebase supports adding labels via the addKey method but that parameter is not available in the rpc.

This is the rpc that needs to be updated to support labels:
rpc api:

chia-blockchain/chia/wallet/wallet_rpc_api.py

Line 793 in 73cb547

async def add_key(self, request: AddKey) -> AddKeyResponse:

rpc client:

chia-blockchain/chia/wallet/wallet_rpc_client.py

Line 231 in 73cb547

async def add_key(self, request: AddKey) -> AddKeyResponse:

rpc types:

chia-blockchain/chia/wallet/wallet_request_types.py

Line 125 in 73cb547

@dataclass(frozen=True)

This is the addKey method in keychain server which does support the label:

chia-blockchain/chia/daemon/keychain_server.py

Line 211 in 73cb547

async def add_key(self, request: dict[str, Any]) -> dict[str, Any]: