feat: add copybara-base job

Change-Id: I0b5aa5b72d00612d3444cc714fb8ad1d983ace72
diff --git a/playbooks/copybara-base/pre.yaml b/playbooks/copybara-base/pre.yaml
new file mode 100644
index 0000000..4c4f314
--- /dev/null
+++ b/playbooks/copybara-base/pre.yaml
@@ -0,0 +1,5 @@
+- hosts: all
+  roles:
+    - role: add-copybara-credential-store
+      vars:
+        git_credentials: copybara_secrets.git_credentials