qmllint: revisit/optimize checking for required properties

From the crash at https://bugreports.qt.io/browse/QTBUG-136998 and the patch at https://codereview.qt-project.org/c/qt/qtdeclarative/+/646875, it seems that we might want to revisit/optimize the required properties check in qmllint.

We need to iterate over base types to find property definitions, property bindings and property requirements. We also need to search children of base types due to aliases to required properties. These two axes are currently mixed together and this causes issues. Especially with the scopesToSearch list.

Maybe a better approach for all this would be to collect all properties, bindings, requirements and alises for each scope and only then perform the checks. This would also ensure that our warnings provide the necessary information. Right now we just hope that what we insert into the warning is correct.