Fix `get-pos-property' for the new overlay implementation.

Fix `get-pos-property' for the new overlay implementation.

Some of the trickier edge cases weren't handled properly.  See
bug#58706.

* src/editfns.c (overlays_around): Extend the search range past POS by
one to fetch overlays beginning at POS.  Fetch empty overlays, as they
may be extended by an insertion and thus be relevant to
`get-pos-property'.  Make a note that the function now, unfortunately,
may return out of range overlays.
(Fget_pos_property): Deal with 'overlays_around' returning out of
range overlays.