AuthN: set org id for authentication request in service (#60528)

* AuthN: Replicate functionallity to get org id for request

* Authn: parse org id for the request and populate the auth request with
it

* AuthN: add simple mock for client to use in test

* AuthN: add tests to verify that authentication is called with correct
org id

* AuthN: Add ClientParams to mock

* AuthN: Fix flaky org id selection

pkg/services/authn/authntest/mock.go

@@ -0,0 +1,36 @@
+package authntest
+
+import (
+	"context"
+
+	"github.com/grafana/grafana/pkg/services/authn"
+)
+
+var _ authn.Client = new(MockClient)
+
+type MockClient struct {
+	AuthenticateFunc func(ctx context.Context, r *authn.Request) (*authn.Identity, error)
+	ClientParamsFunc func() *authn.ClientParams
+	TestFunc         func(ctx context.Context, r *authn.Request) bool
+}
+
+func (m MockClient) Authenticate(ctx context.Context, r *authn.Request) (*authn.Identity, error) {
+	if m.AuthenticateFunc != nil {
+		return m.AuthenticateFunc(ctx, r)
+	}
+	return nil, nil
+}
+
+func (m MockClient) ClientParams() *authn.ClientParams {
+	if m.ClientParamsFunc != nil {
+		return m.ClientParamsFunc()
+	}
+	return nil
+}
+
+func (m MockClient) Test(ctx context.Context, r *authn.Request) bool {
+	if m.TestFunc != nil {
+		return m.TestFunc(ctx, r)
+	}
+	return false
+}