Add batched extrinsics for setting weights

[gztensor]

Issue: The utility pallet batching extrinsics require users to pay fees proportionally to the number of batched extrinsics, despite the set_weights being free. There's also chain bloating issue for multiple set_weights being called.

Solution: Add methods batch_set_weights and batch_commit_weights that would allow to set/commit weights to the multiple subnets from one hotkey using one extrinsic.

AC:

• Extrinsics
• unit tests for happy path
• unit tests for failures
• e2e tests for happy path
• e2e tests for rate limiting

[gztensor]

PR: #1022