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/query/query_test.go

@@ -462,7 +462,7 @@ func setup(t *testing.T) *testContext {
 	t.Helper()
 	pc := &fakePluginClient{}
 	dc := &fakeDataSourceCache{cache: dss}
-	rv := &fakePluginRequestValidator{}
+	rv := &fakeDataSourceRequestValidator{}
 
 	sqlStore, cfg := db.InitTestDBWithCfg(t)
 	secretsService := secretsmng.SetupTestService(t, fakes.NewFakeSecretsStore())
@@ -497,7 +497,7 @@ func setup(t *testing.T) *testContext {
 type testContext struct {
 	pluginContext          *fakePluginClient
 	secretStore            secretskvs.SecretsKVStore
-	pluginRequestValidator *fakePluginRequestValidator
+	pluginRequestValidator *fakeDataSourceRequestValidator
 	queryService           *ServiceImpl // implementation belonging to this package
 	signedInUser           *user.SignedInUser
 }
@@ -518,11 +518,11 @@ func metricRequestWithQueries(t *testing.T, rawQueries ...string) dtos.MetricReq
 	}
 }
 
-type fakePluginRequestValidator struct {
+type fakeDataSourceRequestValidator struct {
 	err error
 }
 
-func (rv *fakePluginRequestValidator) Validate(dsURL string, req *http.Request) error {
+func (rv *fakeDataSourceRequestValidator) Validate(ds *datasources.DataSource, req *http.Request) error {
 	return rv.err
 }