TIGLViewer: Use GLOB_RECURSE in CMake for src files, no more need for manual addition of .h, .cpp or .ui files

[joergbrech]

Description

The title sais it all.

How Has This Been Tested?

TiGLViewer still builds locally and in CI.

Screenshots, that help to understand the changes(if applicable):

Checklist:

Task	Finished	Reviewer Approved
At least one test for the new functionality was added.	yes does not apply	OK
New classes have been added to the Python interface.	yes does not apply	OK
The code is properly documented with doxygen docstrings	yes does not apply	OK
Changes are documented at the top of ChangeLog.md	yes does not apply	OK

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 69.50%. Comparing base (4b34202) to head (222bbee).
Report is 2 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1052   +/-   ##
=======================================
  Coverage   69.50%   69.50%           
=======================================
  Files         301      301           
  Lines       26912    26912           
=======================================
  Hits        18705    18705           
  Misses       8207     8207           

Flag	Coverage Δ
unittests	69.50% <ø> (ø)

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[svengoldberg]

Looks good to me!