Due to BIC we can't change doNameFilter(); since it was a convenience
function of sorts, just replace the one time it was actually used and
use a for loop directly to iterate over the regex patterns.
Add TODO KF6 notes to remove doNameFilter() and doMimeFilter(), two
virtual methods that have no users (c.f. the review).
Port QRegExp::exactMatch() with QRegularExpression::anchoredPattern(),
and QRegExp::Wildcard with QRegularExpression::wildcardToRegularExpression().
Note that setNameFilter() has some users, it took a QString param.,
which is used as the pattern for a QRegularExpression, but there are
differences between valid QRegExp and QRegularExpression patterns.