Tempo: Search for Traces by querying Loki directly from Tempo (#33308)

* Loki query from Tempo UI

- add query type selector to tempo
- introduce linkedDatasource concept that runs queries on behalf of another datasource
- Tempo uses Loki's query field and Loki's derived fields to find a trace matcher
- Tempo uses the trace-to-logs mechanism to determine which dataource is linked

Loki data loads successfully via tempo

Extracted result transformers

Skip null values

Show trace on list id click

Query type selector

Use linked field trace regexp

* Review feedback

public/app/plugins/datasource/loki/components/LokiQueryField.tsx

@@ -92,7 +92,7 @@ export class LokiQueryField extends React.PureComponent<LokiQueryFieldProps, Lok
     ];
   }
 
-  async componentDidUpdate() {
+  async componentDidMount() {
     await this.props.datasource.languageProvider.start();
     this.setState({ labelsLoaded: true });
   }