Add more stackdriver service monitoring datasources

[emilymye]

Add ability to add datasources for:

• cloud endpoints
• cluster istio (API docs say deprecated but)
• mesh istio

The actual work of creating datasources is small (see example) but the initial test resources that create the related monitoring services have to be bootstrapped separately

Finishing work from #5058

[edwardmedia]

For mesh istio, is it meshUid for meshid ?

From https://cloud.google.com/monitoring/api/ref_v3/rest/v3/services

JSON representation
--
{   "meshUid": string,   "serviceNamespace": string,   "serviceName": string }

From https://istio.io/latest/docs/reference/config/istio.mesh.v1alpha1/

meshId | string | The unique identifier for the service mesh All control planes running in the same service mesh should specify the same mesh ID. Mesh ID is used to label telemetry reports for cases where telemetry from multiple meshes is mixed together.

[edwardmedia]

• cloud endpoints
  has been removed from https://cloud.google.com/monitoring/api/ref_v3/rest/v3/services. Adding that DataSource is out of scope

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you feel this issue should be reopened, we encourage creating a new issue linking back to this one for added context. If you feel I made an error 🤖 🙉 , please reach out to my human friends 👉 [email protected]. Thanks!