This patch morphs MasterPassword.jsm to OSKeyStore.jsm while keeping the same
API, as an adaptor between the API and the native API exposed as nsIOSKeyStore.idl.
Noted that OS Key Store has the concept of "recovery phrase" that we won't
be adopting here. The recovery phrase, together with our label, allow
the user to re-create the same key in OS key store.
Test case changes are needed because we have started asking for login in
places where we'll only do previously when "master password is enabled".
This also made some "when master password is enabled" tests invalid because
it is always considered enabled.
Some more test changes are needed simply because they previously rely on the
stable order of microtask resolutions (and the stable # of promises for a
specific operation). That has certainly changed with OSKeyStore.
The credit card form autofill is only enabled on Nightly.
Differential Revision: https://phabricator.services.mozilla.com/D4498
024a78bd94