tests: added test if CP1253-UTF8-CP1253 is lossless

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42017 4005530d-fff6-0310-9dd1-cebe43e6787f
lazutils: made codepage conversion 1253 to UTF8 and back to 1253 lossless

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@42018 4005530d-fff6-0310-9dd1-cebe43e6787f