Explore: Queries the datasource once per run query and uses DataStreamObserver (#17263)

* Refactor: Removes replaceUrl from actions

* Refactor: Moves saveState thunk to epic

* Refactor: Moves thunks to epics

* Wip: removes resulttype and queries once

* Refactor: LiveTailing uses observer in query

* Refactor: Creates epics folder for epics and move back actioncreators

* Tests: Adds tests for epics and reducer

* Fix: Checks for undefined as well

* Refactor: Cleans up previous live tailing implementation

* Chore: merge with master

* Fix: Fixes url issuses and prom graph in Panels

* Refactor: Removes supportsStreaming and adds sockets to DataSourcePluginMeta instead

* Refactor: Changes the way we create TimeSeries

* Refactor: Renames sockets to streaming

* Refactor: Changes the way Explore does incremental updates

* Refactor: Removes unused method

* Refactor: Adds back Loading indication

public/app/features/explore/LogsContainer.tsx

@@ -13,6 +13,7 @@ import {
   LogsModel,
   LogRowModel,
   LogsDedupStrategy,
+  LoadingState,
 } from '@grafana/ui';
 
 import { ExploreId, ExploreItemState } from 'app/types/explore';
@@ -151,14 +152,14 @@ function mapStateToProps(state: StoreState, { exploreId }) {
   const {
     logsHighlighterExpressions,
     logsResult,
-    logIsLoading,
+    loadingState,
     scanning,
     scanRange,
     range,
     datasourceInstance,
     isLive,
   } = item;
-  const loading = logIsLoading;
+  const loading = loadingState === LoadingState.Loading || loadingState === LoadingState.Streaming;
   const { dedupStrategy } = exploreItemUIStateSelector(item);
   const hiddenLogLevels = new Set(item.hiddenLogLevels);
   const dedupedResult = deduplicatedLogsSelector(item);