crypto: AuthoritySignature commits to epoch id

[joyqvq]

https://github.com/MystenLabs/sui/issues/5127

[lxfind]

Is there a plan to use different key for each validator at each epoch?

[joyqvq]

Is there a plan to use different key for each validator at each epoch?

not that I am aware of, its a good idea though, but require some non-trivial work.