Google Cloud Monitor: Prom query editor (#73503)

* revert

* works but needs clean up and tests

* clean up

* remove any

* change confusing query var to expr

* oops

* add test

* lint

* cleanup

* update docs

* Update public/app/plugins/datasource/cloud-monitoring/components/PromQLEditor.tsx

Co-authored-by: Andreas Christou <andreas.christou@grafana.com>

* nit

* lint fix?

* remove comment from cue

* go linter

* removing parsing stuff parseresponse func

---------

Co-authored-by: Andreas Christou <andreas.christou@grafana.com>

docs/sources/datasources/google-cloud-monitoring/query-editor/index.md

@@ -218,8 +218,6 @@ To understand basic MQL concepts, refer to [Introduction to Monitoring Query Lan
 **To create an MQL query:**
 
 1. Select the **Metrics** option in the **Query Type** dropdown.
-1. Select **<> Edit MQL** next to the **Query Type** field.
-   This toggles the MQL query builder mode.
 1. Select a project from the **Project** dropdown.
 1. Enter your MQL query in the text area.
 
@@ -274,6 +272,15 @@ The **Alias By** field helps you control the format of legend keys for SLO queri
 
 SLO queries use the same alignment period functionality as [metric queries](#define-the-alignment-period).
 
+### Create a Prometheus query
+
+**To create an Prometheus query:**
+
+1. Select the **PromQL** option in the **Query Type** dropdown.
+1. Select a project from the **Project** dropdown.
+1. Enter your Prometheus query in the text area.
+1. Enter a Min Step interval. The **Min step** setting defines the lower bounds on the interval between data points. For example, set this to `1h` to hint that measurements are taken hourly. This setting supports the `$__interval` and `$__rate_interval` macros.
+
 ## Apply annotations
 
 {{< figure src="/static/img/docs/google-cloud-monitoring/annotations-8-0.png" max-width= "400px" class="docs-image--right" >}}