[lib][web][native] Delete keyserver accounts when deleting identity account

Summary:
issue: ENG-6502
We want to have a singe action for deleting identity account and keyserver accounts, and an action for deleting just a keyserver account (for when the user disconnects from a keyserver)

Test Plan:
Tested that it is possible to delete account from both web and native and no errors apprear. Tested that if callback returned from useDeleteAccount throws on web, an error message is displayed in the modal.
Tested that when the deletion appears to have been succeful, the user is removed from keyserver db

Reviewers: varun, michal, ashoat

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D10756