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

docs/sources/developers/kinds/composable/googlecloudmonitoringdataquery/schema-reference.md

@@ -0,0 +1,19 @@
+---
+keywords:
+  - grafana
+  - schema
+title: GoogleCloudMonitoringDataQuery kind
+---
+> Both documentation generation and kinds schemas are in active development and subject to change without prior notice.
+
+## GoogleCloudMonitoringDataQuery
+
+#### Maturity: [merged](../../../maturity/#merged)
+#### Version: 0.0
+
+
+
+| Property | Type | Required | Default | Description |
+|----------|------|----------|---------|-------------|
+
+