Shared Azure middleware between Azure Monitor and Prometheus datasources (#46002)

* Scopes in Azure middleware

* Enable Azure middleware without feature flag

* Use common Azure middleware in Azure Monitor

* Apply feature flag to JsonData configuration of Azure auth

* Enforce feature flag in Prometheus datasource

* Prometheus provider tests

* Datasource service tests

* Fix http client provider tests

* Pass sdkhttpclient.Options by reference

* Add middleware to httpclient.Options

* Remove dependency on Grafana settings

* Unit-tests updated

* Fix ds_proxy_test

* Fix service_test

pkg/services/featuremgmt/registry.go

@@ -20,7 +20,7 @@ var (
 		},
 		{
 			Name:        "httpclientprovider_azure_auth",
-			Description: "use http client for azure auth",
+			Description: "Experimental. Allow datasources to configure Azure authentication directly via JsonData",
 			State:       FeatureStateBeta,
 		},
 		{
@@ -112,7 +112,7 @@ var (
 		},
 		{
 			Name:        "prometheus_azure_auth",
-			Description: "Use azure authentication for prometheus datasource",
+			Description: "Experimental. Azure authentication for Prometheus datasource",
 			State:       FeatureStateBeta,
 		},
 		{

pkg/services/featuremgmt/toggles_gen.go

@@ -16,7 +16,7 @@ const (
 	FlagEnvelopeEncryption = "envelopeEncryption"
 
 	// FlagHttpclientproviderAzureAuth
-	// use http client for azure auth
+	// Experimental. Allow datasources to configure Azure authentication directly via JsonData
 	FlagHttpclientproviderAzureAuth = "httpclientprovider_azure_auth"
 
 	// FlagServiceAccounts
@@ -84,7 +84,7 @@ const (
 	FlagAccesscontrolBuiltins = "accesscontrol-builtins"
 
 	// FlagPrometheusAzureAuth
-	// Use azure authentication for prometheus datasource
+	// Experimental. Azure authentication for Prometheus datasource
 	FlagPrometheusAzureAuth = "prometheus_azure_auth"
 
 	// FlagInfluxdbBackendMigration