Tailor QtCreator to be able to edit, patch and build Qt from source

Building Qt should be easy from Qt Creator, yet it's not possible out-of-the-box.

The guides for 5 and 6 also only show how to build via the command line.
(I haven' even found guides on how to approach patching just a single library).

It should be easy to:

• Build from scratch just by pressing play
  • Targets should be selectable
  • Other options should be selectable and/or auto-detected

It should also be easier to:

• Create a copy of a version
• Patch just part of the code
• Build only the parts that need to be rebuilt (default target: all detected targets)