tests for assets pallet (#8487)

* tests for assets

* Update frame/assets/src/tests.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* Update frame/assets/src/tests.rs

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

* add force asset status check

* remove TODO

* actually remove TODO

* add force asset status tests

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>