Ability to create StakeAuthorization MsgGrant messages

[nooxx]

Hello, I feel like it is currently not possible to create MsgGrant of type "/cosmos.staking.v1beta1.StakeAuthorization" like on this tx: https://explorer.injective.network/transaction/0x9ee91f73c4ffc3c777aa0d5c85c86d9750abf20d061609f3850581ece747b4f6/

Unless I am missing something. It would be a great to support them.

Best

[bangjelkoski]

Hey, feel free to add this particular authorization on the SDK and I'll review the PR.