Summary of Changes

Two main things done in this PR:

• Added a new "view search action" event for telemetry
• Added basic counting of (unfiltered) items returned from getChildren() to then show in the view message (and send with telemetry)

Any additional details or context that should be provided?

I was on the fence about the "total count" idea since we can expand the full tree all the time, so it's more of a "total count so far based on what items have been expanded".

I also have some nits about the mixed resource types all being counted together, so you don't get a more elaborate count like Showing 13 of 50 topics and 4 of 35 schema subjects for "searchstring". We could start counting them individually, but that may end up being more noisy than what's necessary for now.

Pull request checklist

Please check if your PR fulfills the following (if applicable):

Tests

• Added new
• Updated existing
• Deleted existing

Other

• All new disposables (event listeners, views, channels, etc.) collected as for eventual cleanup?

• Does anything in this PR need to be mentioned in the user-facing CHANGELOG or README?
• Have you validated this change locally by packaging and installing the extension .vsix file?

  gulp clicktest