CloudMonitoring: Initial GCM Schema (#67739)

* Initial GCM schema work

- Split types for convenience
- Update conditionals where needed
- Update type references

* Add additional supporting types

* Add some more accessory and legacy types

* Add missing type

* Rename backend folder

* Add missing generated file

* Review

.betterer.results

@@ -3774,7 +3774,7 @@ exports[`better eslint`] = {
       [0, 0, 0, "Do not use any type assertions.", "1"],
       [0, 0, 0, "Unexpected any. Specify a different type.", "2"]
     ],
-    "public/app/plugins/datasource/cloud-monitoring/types.ts:5381": [
+    "public/app/plugins/datasource/cloud-monitoring/types/types.ts:5381": [
       [0, 0, 0, "Unexpected any. Specify a different type.", "0"]
     ],
     "public/app/plugins/datasource/cloudwatch/components/ConfigEditor.test.tsx:5381": [