feat: header based acls (#337)

* feat: add header decoder

* feat: allow for dash substitute over slash for environments like kubernetes

* feat: use decoded headers in proxy controller

* refactor: simplify decode header to node function

* refactor: use stdlib prefix check in header decoder

* fix: lowercase key and filter before comparing

internal/utils/decoders/label_decoder.go

@@ -0,0 +1,19 @@
+package decoders
+
+import (
+	"tinyauth/internal/config"
+
+	"github.com/traefik/paerser/parser"
+)
+
+func DecodeLabels(labels map[string]string) (config.AppConfigs, error) {
+	var appLabels config.AppConfigs
+
+	err := parser.Decode(labels, &appLabels, "tinyauth", "tinyauth.apps")
+
+	if err != nil {
+		return config.AppConfigs{}, err
+	}
+
+	return appLabels, nil
+}