sc-consensus-manual-seal uses Finalizer trait for finalization instead of Backend. (#5469)

* manual-seal uses Finalizer trait for finalization instead of Backend

* fix tests

* use Transaction type

* refactor import_queue

* ugh

* line-width

* Update client/consensus/manual-seal/src/lib.rs

Co-Authored-By: Joshy Orndorff <[email protected]>

* fix tests

* update docs

* Update client/consensus/manual-seal/src/seal_new_block.rs

Co-Authored-By: André Silva <[email protected]>

* Don't auto-finalize on verification

* Explicity don't finalize on import.

Co-authored-by: Joshy Orndorff <[email protected]>
Co-authored-by: Joshy Orndorff <[email protected]>
Co-authored-by: André Silva <[email protected]>