Port KRecursiveFilterProxyModel to QSortFilterProxyModel

Summary:
Set setRecursiveFilteringEnabled(true) by default. Set required Qt
version to 5.10.0, that's where QSortFilterProxyModel gained recursive
filtering capability.

Test Plan:
make && ctest. All unit tests pass except for a couple of them, but
these same ones fail on master too.

Reviewers: ervin

Reviewed By: ervin

Maniphest Tasks: T12269

Differential Revision: https://phabricator.kde.org/D26562