Introduce new preview auto-scaling mode for ARC. (#2153)

Co-authored-by: Cory Miller <cory-miller@github.com>
Co-authored-by: Nikola Jokic <nikola-jokic@github.com>
Co-authored-by: Ava Stancu <AvaStancu@github.com>
Co-authored-by: Ferenc Hammerl <fhammerl@github.com>
Co-authored-by: Francesco Renzi <rentziass@github.com>
Co-authored-by: Bassem Dghaidi <Link-@github.com>

github/actions/fake/multi_client.go

@@ -0,0 +1,43 @@
+package fake
+
+import (
+	"context"
+
+	"github.com/actions/actions-runner-controller/github/actions"
+)
+
+type MultiClientOption func(*fakeMultiClient)
+
+func WithDefaultClient(client actions.ActionsService, err error) MultiClientOption {
+	return func(f *fakeMultiClient) {
+		f.defaultClient = client
+		f.defaultErr = err
+	}
+}
+
+type fakeMultiClient struct {
+	defaultClient actions.ActionsService
+	defaultErr    error
+}
+
+func NewMultiClient(opts ...MultiClientOption) actions.MultiClient {
+	f := &fakeMultiClient{}
+
+	for _, opt := range opts {
+		opt(f)
+	}
+
+	if f.defaultClient == nil {
+		f.defaultClient = NewFakeClient()
+	}
+
+	return f
+}
+
+func (f *fakeMultiClient) GetClientFor(ctx context.Context, githubConfigURL string, creds actions.ActionsAuth, namespace string) (actions.ActionsService, error) {
+	return f.defaultClient, f.defaultErr
+}
+
+func (f *fakeMultiClient) GetClientFromSecret(ctx context.Context, githubConfigURL, namespace string, secretData actions.KubernetesSecretData) (actions.ActionsService, error) {
+	return f.defaultClient, f.defaultErr
+}