Port start page to release (#12365)

* start page experiment and fixes (#12339)

* move EnableStartPage enum to groups.ts

* - remove the command from the experiment
- fix the start page not loading when you go back
to a priviews version and then updating again
- update some labels in the start page
- update the sample notebook to include run by line
- the sample notebook now has a title
- updated the images from the sample notebook

* oops

* oops

* -add messages to open folder and workspace
-add telemetry to measure if the webview error happens
-give space between bullet points
-add link to enable experiments to the sample notebook
-get the release notes from a different file
-fix bullet points in the sample notebook
-sample notebook now opens with a counter in the title

* fix a unit test

* final changes

* final final changes

* final^3 changes

* removed run by line from the sample notebook

* Fixup after merge

Co-authored-by: David Kutugata <dakutuga@microsoft.com>

src/client/common/experiments/groups.ts

@@ -99,3 +99,8 @@ export enum NotebookEditorSupport {
 export enum EnableStartPage {
     experiment = 'EnableStartPage'
 }
+
+// Experiment to turn on the start page
+export enum EnableStartPage {
+    experiment = 'EnableStartPage'
+}