Implement a server-side config service interface.

luci_config/server/cfgclient/backend/authority_string.go

Index: luci_config/server/cfgclient/backend/authority_string.go
diff --git a/luci_config/server/cfgclient/backend/authority_string.go b/luci_config/server/cfgclient/backend/authority_string.go
new file mode 100644
index 0000000000000000000000000000000000000000..fa884424620face67f2f46d4779f3cc310fd8ce3
--- /dev/null
+++ b/luci_config/server/cfgclient/backend/authority_string.go
@@ -0,0 +1,16 @@
+// Code generated by "stringer -type Authority"; DO NOT EDIT
+
+package backend
+
+import "fmt"
+
+const _Authority_name = "AsAnonymousAsServiceAsUser"
+
+var _Authority_index = [...]uint8{0, 11, 20, 26}
+
+func (i Authority) String() string {
+	if i < 0 || i >= Authority(len(_Authority_index)-1) {
+		return fmt.Sprintf("Authority(%d)", i)
+	}
+	return _Authority_name[_Authority_index[i]:_Authority_index[i+1]]
+}