In "directories only" mode, it was impossible to actually accept a selection. Fix this by allowing to accept the currently shown directory.
RFC because I'm wondering whether I'm missing something obvious.
Even building KIO at 0829537a doesn't fix a
KFile::Mode::Directory | KFile::Mode::ExistingOnly mode.
Also, I didn't really study how slotOk interacts with the rest of the class, so this might break some other edge cases...