Port KRecursiveFilterProxyModel to QSortFilterProxyModel

Summary:
Use QSortFilterProxyModel::filterAcceptsRow() instead of
KRecursiveFilterProxyModel::acceptRow().

Set setRecursiveFilteringEnabled(true) by default.

Test Plan: make && ctest.

Reviewers: mwolff

Reviewed By: mwolff

Maniphest Tasks: T12269

Differential Revision: https://phabricator.kde.org/D26568