When a user restores to a new phone, their TPM will no longer be able to
decrypt the encrypted credentials.
We have code already in place to delete "invalid" sites, which cleans
these up by removing them.
However, when trying to save a new site, Android continues to try to use
the old keys which are no longer decryptable. So, when saving new
encrypted files, simply reset the crypto keys if we are unable to
encrypt.
Previously VPN permissions were requested when the UI was loaded. If the
user denied the permissions it would have to be force stopped and
reopened to get another permission request grant.
Additionally, when requesting VPN permissions Android will kill any
other running VPN service. This avoids that behavior unless a site is
explicitly started.
Also disables the app from showing up in the "Always On" settings.