Transformations: add 'prepare time series' transformer (#36737)

* adding transformer that will stretch a data frame from wide to long.

* added a UI for the stretch frames transformer.

* refactored according to feedback.

* removed unused dep.

* making sure it is being displayed.

* minor adjustments.

* move stretch to prepare

* improved readability of tests.

* refactored to use a function component syntax.

Co-authored-by: Marcus Andersson <marcus.andersson@grafana.com>

packages/grafana-data/src/transformations/transformers/ids.ts

@@ -25,4 +25,5 @@ export enum DataTransformerID {
   histogram = 'histogram',
   configFromData = 'configFromData',
   rowsToFields = 'rowsToFields',
+  prepareTimeSeries = 'prepareTimeSeries',
 }