Extensions viewlet: 'Check for Extension Updates' should us a modal dialog to confirm

[egamma]

Testing #114922

Since the user initiated the action to check for extension update, the confirmation that no extension needs to be updated should be shown in a modal dialog (same as when you check for an update of VS Code).

[sandy081]

@egamma It used to be dialog before and changed to notification because to be consistent with all other extensions update information messages which are shown as notifications - #98761

[sandy081]

I heard that this brought up in our stand up and want to revisit.

As said, this was made a notification because to be consistent with this action's behavior - to always show a notification to inform about updates.

I would like to change this behaviour as follows:

• If there are updates, show the outdated extensions in the extensions view otherwise show a dialog that there are no updates