* store block number ++ state root in parachains pallet

* fixed parachains finality APIs

* (test commit)

* removed test code

* deduplicated code a bit

* removed commented code

* spelling

* Update modules/parachains/src/lib.rs

Co-authored-by: Adrian Catangiu <[email protected]>

* Update modules/parachains/src/lib.rs

Co-authored-by: Adrian Catangiu <[email protected]>

* Update modules/parachains/src/mock.rs

Co-authored-by: Adrian Catangiu <[email protected]>

* added comment

Co-authored-by: Adrian Catangiu <[email protected]>