[CI] Add clippy checks to stx-genesis subrepo

[jferrant]

Depends on : #3940

Add clippy checks for the stx-genesis subrepo to CI. To run clippy on ONLY stx-genesis, use cargo clippy -p stx-genesis --no-deps --tests --all-features

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.