qdoc: generatedoutput autotest: Test more C++ -related commands

Improve the coverage of C++ test with the following cases:
 * \macro taking an argument
 * A non-related member (above macro) associated with a class
 * \inheaderfile command
 * \since command

Fix incorrect expected output since fixing the bug mentioned in
the task number.

Task-number: QTBUG-77960
Change-Id: I6010cab9ab0a86a1897a38a397b8d7ba8155f95a
Reviewed-by: Paul Wicking <paul.wicking@qt.io>