AuthN: Rebuild Authenticate so we only have to call it once in context handler (#61705)

* API: Add reqSignedIn to router groups

* AuthN: Add fall through in context handler

* AuthN: Add IsAnonymous field

* AuthN: add priority to context aware clients

* ContextHandler: Add comment

* AuthN: Add a simple priority queue

* AuthN: Add Name to client interface

* AuthN: register clients with function

* AuthN: update mock and fake to implement interface

* AuthN: rewrite test without reflection

* AuthN: add comment

* AuthN: fix queue insert

* AuthN: rewrite tests

* AuthN: make the queue generic so we can reuse it for hooks

* ContextHandler: Add fixme for auth headers

* AuthN: remove unused variable

* AuthN: use multierror

* AuthN: write proper tests for queue

* AuthN: Add queue item that can store the value and priority

Co-authored-by: Jo <joao.guerreiro@grafana.com>

pkg/services/authn/clients/basic.go

@@ -13,7 +13,7 @@ var (
 	errDecodingBasicAuthHeader = errutil.NewBase(errutil.StatusBadRequest, "basic-auth.invalid-header", errutil.WithPublicMessage("Invalid Basic Auth Header"))
 )
 
-var _ authn.Client = new(Basic)
+var _ authn.ContextAwareClient = new(Basic)
 
 func ProvideBasic(client authn.PasswordClient) *Basic {
 	return &Basic{client}
@@ -23,6 +23,10 @@ type Basic struct {
 	client authn.PasswordClient
 }
 
+func (c *Basic) Name() string {
+	return authn.ClientBasic
+}
+
 func (c *Basic) Authenticate(ctx context.Context, r *authn.Request) (*authn.Identity, error) {
 	username, password, err := util.DecodeBasicAuthHeader(getBasicAuthHeaderFromRequest(r))
 	if err != nil {
@@ -36,6 +40,10 @@ func (c *Basic) Test(ctx context.Context, r *authn.Request) bool {
 	return looksLikeBasicAuthRequest(r)
 }
 
+func (c *Basic) Priority() uint {
+	return 40
+}
+
 func looksLikeBasicAuthRequest(r *authn.Request) bool {
 	return getBasicAuthHeaderFromRequest(r) != ""
 }