OAuth2: Add Client Credentials Authentication #213 #782 #808 #3730 #3943

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>

pkg/clean/scope.go

@@ -0,0 +1,16 @@
+package clean
+
+import (
+	"strings"
+
+	"github.com/photoprism/photoprism/pkg/list"
+)
+
+// Scope sanitizes a string that contains authentication scope identifiers.
+func Scope(s string) string {
+	if s == "" {
+		return ""
+	}
+
+	return list.ParseAttr(strings.ToLower(s)).String()
+}