Add to "tolerance" to `ddbs_distance()`

[rafapereirabr]

Add a tolerance argument to ddbs_distance():

In the {sf} docs:

• tolerance: ignored if st_is_longlat(x) is FALSE; otherwise, if set to a positive value, the first distance smaller than tolerance will be returned, and true distance may be smaller; this may speed up computation. In meters, or a units object convertible to meters.

[rafapereirabr]

DuckDB has no distance function that takes a tolerance argument to stop early at a threshold. This issue would require changes upstream.

[Cidree]

Sure, I think we can close it, and open it again if that's implemented upstream.