IDE: open designer form: rewrote search algorithm for nested classes

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40018 4005530d-fff6-0310-9dd1-cebe43e6787f
IDE: open designer form: store the found fallback component classes

git-svn-id: http://svn.freepascal.org/svn/lazarus/trunk@40019 4005530d-fff6-0310-9dd1-cebe43e6787f