Plugins: Modify interface for plugin validations to allow taking PDC into account (#96089)

* Request interceptor: Do not block PDC

* Apply change after feedback received

* Add test

* Check if secure socks proxy configured for the instance

* Apply suggestions from code review

* Add dedicated service for datasource request URL validation (#99179)

---------

Co-authored-by: Will Browne <wbrowne@users.noreply.github.com>

pkg/services/datasourceproxy/datasourceproxy_test.go

@@ -94,8 +94,8 @@ func TestDatasourceProxy_proxyDatasourceRequest(t *testing.T) {
 			}}
 
 			p := DataSourceProxyService{
-				PluginRequestValidator: &fakePluginRequestValidator{},
-				pluginStore:            pluginStore,
+				DataSourceRequestValidator: &fakeDataSourceRequestValidator{},
+				pluginStore:                pluginStore,
 			}
 
 			responseRecorder := httptest.NewRecorder()
@@ -129,8 +129,8 @@ func TestDatasourceProxy_proxyDatasourceRequest(t *testing.T) {
 	}
 }
 
-type fakePluginRequestValidator struct{}
+type fakeDataSourceRequestValidator struct{}
 
-func (rv *fakePluginRequestValidator) Validate(_ string, _ *http.Request) error {
+func (rv *fakeDataSourceRequestValidator) Validate(_ *datasources.DataSource, _ *http.Request) error {
 	return nil
 }