Adding tests to Create forced operation with different contexts.

Verify that the clients (for ex: clients with `vold` context) with
`req_forced_op` permission are allowed to create forced (unpruneable)
operations otherwise the creation of forced operation is denied.

Bug: 194359114
Test: atest keystore2_client_test
Change-Id: I73d85ac127274e623095e233368b0211f6738d6e
2 files changed