Add lock id to return value of MsgSuperfluidUndelegateAndUnbondLockResponse

[mattverse]

What is the purpose of the change

MsgSuperfluidUndelegateAndUnbondLock currently does not return any value.
However, the method being called does: returns existing lock id when unlocking same amount of tokens that was in the lock, returns new lock id when a partial unlock has happened and a new lock has been created.

Missing this return value results in external integrators having to try find a different way of finding out the new lock id that have been created.

This PR fixes the problem via returning the lock id.

Brief Changelog

• Add lock id to return value of MsgSuperfluidUndelegateAndUnbondLockResponse

Testing and Verifying

This change is a trivial rework / code cleanup without any test coverage.

Documentation and Release Note

• Does this pull request introduce a new feature or user-facing behavior changes? (yes / no)
• Is a relevant changelog entry added to the Unreleased section in CHANGELOG.md? (yes / no)
• How is the feature or change documented? (not applicable / specification (x/<module>/spec/) / Osmosis docs repo / not documented)

[stackman27]

LGTM