(feat/explore): Support for new LogQL filtering syntax (#16674)

* (feat/explore): Support for new LogQL filtering syntax

Loki is adding syntax to support chained filtering.
This PR adapts Grafana to support this.

- Send only `query` parameter in loki request
- Automatically wrap search text in simple syntax, e.g., `{} foo` is
sent as `{} |~ "foo"`.


* Adapted to regexp parameter staying on in Loki

* Dont wrap single regexp in new filter syntax

* Fix datasource test

* Fallback regexp parameter for legacy queries

* Fix search highlighting

* Make highlighting work for filter chains

* Fix datasource test

packages/grafana-ui/src/types/data.ts

@@ -21,7 +21,7 @@ export interface QueryResultMeta {
   requestId?: string;
 
   // Used in Explore for highlighting
-  search?: string;
+  searchWords?: string[];
 
   // Used in Explore to show limit applied to search result
   limit?: number;

packages/grafana-ui/src/types/datasource.ts

@@ -194,7 +194,7 @@ export abstract class ExploreDataSourceApi<
   TOptions extends DataSourceJsonData = DataSourceJsonData
 > extends DataSourceApi<TQuery, TOptions> {
   modifyQuery?(query: TQuery, action: QueryFixAction): TQuery;
-  getHighlighterExpression?(query: TQuery): string;
+  getHighlighterExpression?(query: TQuery): string[];
   languageProvider?: any;
 }