This adds standard OAuth2 client credentials and bearer token support as
well as scope-based authorization checks for REST API clients. Note that
this initial implementation should not be used in production and that
the access token limit has not been implemented yet.
Signed-off-by: Michael Mayer <michael@photoprism.app>
Expose a new API which can be scraped by prometheus to gather useful
metrics from an instance. The new endpoint exposes photoprism build
version information, golang version, edition and various count metrics.
