tizen_app.prf: signing moved to external build step.

Additionally build_data and qt.conf files are generated
in build step instead of the install step. In install step
generated files and chosen libraries are copied
to temporary packaging directory.

Change-Id: Ifc375607c2f33fd9ad8dc28f5769acf9afa6b2b7
Reviewed-by: Jarosław Staniek <staniek@kde.org>