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>

config/rbac/ephemeralrunnerset_editor_role.yaml

@@ -0,0 +1,24 @@
+# permissions for end users to edit ephemeralrunnersets.
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  name: ephemeralrunnerset-editor-role
+rules:
+- apiGroups:
+  - actions.github.com
+  resources:
+  - ephemeralrunnersets
+  verbs:
+  - create
+  - delete
+  - get
+  - list
+  - patch
+  - update
+  - watch
+- apiGroups:
+  - actions.github.com
+  resources:
+  - ephemeralrunnersets/status
+  verbs:
+  - get