Use the side-panel for more than an onboarding tutorial #2715
Description
Currently, the default view on the side panel is a welcome message that summarizes GitLens features. It is useful for a new user, but otherwise redundant. On the other hand, it has precious real estate, occupying a part of the screen that is multi-purpose (file explorer, and other extensions use it). It would be nice if it was to make use of that space to display useful information after on-boarding is complete. For example, it could display a list of recent commits or a diff file explorer. In order to not regress on discoverability, the linked features could be part of the toolbar at the top.
