Find built-in tool corresponding to quick tool at runtime

In this way it is possible to drop the `sourceId` attribute from the quick tools definition. This simplifies the code logic and makes it easier to update user settings from the previous version of Okular (because there is no need to add the attribute `sourceId`

This also fixes the crash due to the fact that `sourceId` was not correctly created when a quick annotation is created from the Annotation page of Okualr Settings.

BUG: 424810
FIXED-IN: 1.11.0