Add unsubscribeByID (#4061)

* adding function unsubscribe by id

* adding an unsubscribe testcase

* adding testcase

* seperated unsubscribebyid to its own method

* adding testcases

* adding await

* fixing testcases

Co-authored-by: Alex <alex.luu@mail.utoronto.ca>
Co-authored-by: Alex <alex@chainsafe.io>