Today we restart the extension host whenever the first folder changes because workspace.rootPath is always set to that first folder and it never used to change after the extension host started once.

If we would not restart the extension host anymore an extension:

• could use workspace.rootPath as before, it would still point to the first folder always (which can be undefined if the workspace contains no folders)
• could subscribe to the onDidChangeWorkspaceFolders event to get notified about updates
• would see the value of workspace.rootPath changing during runtime whenever the first folder changes

//cc @sandy081 @jrieken