[native][lib] update useDeleteDiscardedIdentityAccount to throw

Summary:
we need this hook to throw so that we can catch exceptions in useRegistrationServerCall and alert the user if their account was successfully created but login failed.

Depends on D12335

Test Plan:
applied this patch: https://gist.github.com/vdhanan/0a8bd816ab34cd2df3fdb46a73087f0b

then confirmed that DELETE_ACCOUNT_SUCCESS was dispatched and the Alert was displayed (see screenshot)

Reviewers: ashoat

Reviewed By: ashoat

Subscribers: tomek

Differential Revision: https://phab.comm.dev/D12353