Transform: added merge transform that will merge multiple series/tables into one table (#25490)

* wip: added draft of series to rows.

* wip: building dataFrame structure first and then adding data.

* wip: added some refactorings of the seriesToRows transformer.

* did some refactorings to make the code easier to follow.

* added an editor for the transform.

* renamed some of the test data.

* added docs.

* fixed according to feedback.

* renamved files.

* fixed docs according to feedback.

* fixed so we don't keep labels or config values from.

* removed unused field.

* fixed spelling errors.

* fixed docs according to feedback.

packages/grafana-data/src/datetime/moment_wrapper.ts

@@ -58,6 +58,7 @@ export interface DateTime extends Object {
   fromNow: (withoutSuffix?: boolean) => string;
   from: (formaInput: DateTimeInput) => string;
   isSame: (input?: DateTimeInput, granularity?: DurationUnit) => boolean;
+  isBefore: (input?: DateTimeInput) => boolean;
   isValid: () => boolean;
   local: () => DateTime;
   locale: (locale: string) => DateTime;