Tests: Add standalone test configuration preamble to manual tests

Add the boilerplate standalone test prelude to each manual test, so
that they can be configured with cmake or qt-cmake directly without
the qt-cmake-standalone-test script.

Task-number: QTBUG-95272
Change-Id: Ibeeb7ce41c17d4b7c3c1e6f90d938444c94b83fb
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>