explore: don't parse log levels if provided by field or label (#17180)

If a field or a label named level is returned from datasource that is 
used as log level for the logs result instead of parsing the log level 
from the message.

Closes #17122

packages/grafana-ui/src/utils/logs.ts

@@ -23,6 +23,15 @@ export function getLogLevel(line: string): LogLevel {
   return LogLevel.unknown;
 }
 
+export function getLogLevelFromKey(key: string): LogLevel {
+  const level = (LogLevel as any)[key];
+  if (level) {
+    return level;
+  }
+
+  return LogLevel.unknown;
+}
+
 export function addLogLevelToSeries(series: SeriesData, lineIndex: number): SeriesData {
   return {
     ...series, // Keeps Tags, RefID etc