unify qtquickdesigner cmake files

From history there are different CmakeList files and includes.
 
Main reason was to have tests not compiling against a "big" library but using just the to test code as statically compiled insid the test.

With cmake we are able to define static compile block for all files and then take that or compile that against a shared library interface.

So there is no need to keep two cmake files which list the files anymore.