Canonical: Add the ability to disable `redirect_guess_404_permalink()`.

This also adds a few more filters to make adding redirects easier. Notably:

1. `do_redirect_guess_404_permalink`
2. `pre_redirect_guess_404_permalink`
3. `strict_redirect_guess_404_permalink`

Fixes: #16557.
Props: msafi, nacin, simonwheatley, westi, mboynes, joostdevalk, Lex_Robinson, MikeSchinkel, haukep, paulschreiber, DrewAPicture, ravenswd, esemlabel, stevegibson12, martychc23, DrLightman, jivanpal, neonkowy, laternastudio, apedog, audrasjb, davidbaumwald, Confridin, donmhico, ryotsun. 


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