Add Migrationscript for Firebase Config
Add Migrationscript for Firebase Config

The Registration URL and TTL for enrolling a push token
are actually not part of a firebase configuration.
Thus we move these settings from the firebase config to the
enrollment policy.

Thus these two values can also be used for poll-only
push-tokens.

Closes #2720

privacyidea/privacyidea,privacyidea/privacyidea,privacyidea/privacyidea,privacyidea/privacyidea,privacyidea/privacyidea,privacyidea/privacyidea