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/datasources/models.go

@@ -70,6 +70,16 @@ type DataSource struct {
 
 	Created time.Time `json:"created,omitempty"`
 	Updated time.Time `json:"updated,omitempty"`
+
+	isSecureSocksDSProxyEnabled *bool `xorm:"-"`
+}
+
+func (ds *DataSource) IsSecureSocksDSProxyEnabled() bool {
+	if ds.isSecureSocksDSProxyEnabled == nil {
+		enabled := ds.JsonData != nil && ds.JsonData.Get("enableSecureSocksProxy").MustBool(false)
+		ds.isSecureSocksDSProxyEnabled = &enabled
+	}
+	return *ds.isSecureSocksDSProxyEnabled
 }
 
 type TeamHTTPHeadersJSONData struct {