Further optimize startup time until editor is ready

Focus on optimizing the time it takes from launching Qt Creator from command line until the user is able to edit a file.

Motivation

Make Qt Creator better suited for editing of simple files from command line. Delays at startup causes frustration for users that open/close Qt Creator regularly, and is a large part of the subjective 'heaviness' of an application.

Reproducible setup

TODO

Ideas

• Make License Checker more parallel.
• Switch to Edit mode early on, don't wait until Welcome mode is set up to then switch away from it