tests: added test if CP1254-UTF8-CP1254 is lossless

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42019 4005530d-fff6-0310-9dd1-cebe43e6787f
lazutils: made codepage conversion 1254 to UTF8 and back to 1254 lossless

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42020 4005530d-fff6-0310-9dd1-cebe43e6787f