Only one build system instead of two

[alexmucde]

Currently the DLT Viewer supports two build systems, cmake and qmake.
To reduce the maintenance effort and the possiblility of wrong configurations this should be reduced to one, preferable cmake.
It must be taken care, that all development use cases must be supported:

• Build Scripts for Windows
• Build Scripts for Linux Debian packages (uses currently qmake)
• Development, Debug and Test with QtCreator (uses currently qmake)
• Github Action CI

[hannesa2]

From the CI point of view:

• Windows builds already with cmake
• MacOS builds already with cmake
• Linux builds with qmake and cmake I've no clue if we simply can remove the qmake stuff
• I've no clue about "Development, Debug and Test with QtCreator" at least the CI don't use it (as far as I know). That means it's not tested (and supported ?)

[hannesa2]

With #562 the CI is qmake free

[hannesa2]

With #562 the CI is qmake free

After merge it, the CI is now qmake-free

[vifactor]

very nice! related to #501 (comment)