windeployqt does not support Qt compiled with -libinfix option

With compiling Qt6 with the libinfix option plugins now have the infix inserted in the filename.  Of particular importance this results in the windows platform plugin being called qwindowsINFIX.dll for release or qwindowsINFIXd.dll for debug.

When running windeployqt the error "Unable to find the platform plugin." is reported.  This is because the filter passed to findSharedLibraries in utils.cpp is specifically "qwindows" resulting in only the names "qwindows.dll" and "qwindowsd.dll" being valid.

A workaround is to rename platform plugins to remove the infix parameter.

The solution is probably to add the value of the infix parameter at compile time to the string nameFilter between lines 115 & 116 of utils.cpp.