Problem: tests: testdir is a bit messy
Solution: move test scripts into testdir/util/ directory
src/testdir/ has become a dumping ground mixing test cases with utility
functions. Let's fix this by moving all utility functions into the
testdir/util/ directory
Also a few related changes had to be done:
- Update Filelist
- update README.txt and mention the new directory layout
- fix shadowbuild by linking the util directory into the shadow dir
closes: #17677
Signed-off-by: Christian Brabandt <cb@256bit.org>