Add possibility for multiple signatures to inputs upload

[david-zk]

As we discussed in DMs kms nodes can create multiple signatures, we'd need to query KMS blockchain periodically to refresh the signers and validate their signatures of the requests

@titouantanguy @dartdart26 @antoniupop

[titouantanguy]

Not sure whether removing WaitComputations is related to the multiple signature thingy ?
But adding the repeated for signature LGTM.

[david-zk]

Not sure whether removing WaitComputations is related to the multiple signature thingy ? But adding the repeated for signature LGTM.

Unrelated, just protobuf was regenerated