Port QRegExp::exactMatch() with QRegularExpression::anchoredPattern().
Port QRegExp::Wildcard with QRegularExpression::wildcardToRegularExpression().
Note that QRegularExpression::wildcardToRegularExpression() returns an anchored
pattern.
KFileItemModelFilter still uses QRegExp as there's no equivalent in QRegularExpression
to QRegExp::WildcardUnix.