AzureMonitor: Migrate to backend checkHealth API (#50448)

* Add check health functions for each datasource and generic checkHealth function

* Log backend errors

* Update testDatasource function

- Remove unused testDatasource functions from pseudo datasources

* Switch datasource to extend DataSourceWithBackend

* Improve errors and responses from health endpoint

* Fix backend lint issues

* Remove unneeded frontend tests

* Remove unused/unnecessary datasource methods

* Update types

* Improve message construction

* Stubbing out checkHealth tests

* Update tests

- Remove comments
- Simplify structure

* Update log analytics health check to query data rather than retrieve workspace metadata

* Fix lint issue

* Fix frontend lint issues

* Update pkg/tsdb/azuremonitor/azuremonitor.go

Co-authored-by: Andres Martinez Gotor <andres.martinez@grafana.com>

* Updates based on PR comments

- Don't use deprecated default workspace field
- Handle situation if no workspace is found by notifying user
- Correctly handle health responses

* Remove debug line

* Make use of defined api versions

* Remove field validation functions

* Expose errors in frontend

* Update errors and tests

* Remove instanceSettings

* Update error handling

* Improve error handling and presentation

* Update tests and correctly check error type

* Refactor AzureHealthCheckError and update tests

* Fix lint errors

Co-authored-by: Andres Martinez Gotor <andres.martinez@grafana.com>

pkg/tsdb/azuremonitor/resourcegraph/azure-resource-graph-datasource.go

@@ -46,7 +46,7 @@ type AzureResourceGraphQuery struct {
 	TimeRange         backend.TimeRange
 }
 
-const argAPIVersion = "2021-06-01-preview"
+const ArgAPIVersion = "2021-06-01-preview"
 const argQueryProviderName = "/providers/Microsoft.ResourceGraph/resources"
 
 func (e *AzureResourceGraphDatasource) ResourceRequest(rw http.ResponseWriter, req *http.Request, cli *http.Client) {
@@ -123,7 +123,7 @@ func (e *AzureResourceGraphDatasource) executeQuery(ctx context.Context, query *
 	dataResponse := backend.DataResponse{}
 
 	params := url.Values{}
-	params.Add("api-version", argAPIVersion)
+	params.Add("api-version", ArgAPIVersion)
 
 	dataResponseErrorWithExecuted := func(err error) backend.DataResponse {
 		dataResponse = backend.DataResponse{Error: err}