missing previous link when `offset>0` but `limit > number_matched`

[vincentsarago]

In

pgstac/src/pgstac/sql/004a_collectionsearch.sql

Line 106 in 6da165b

IF _limit <= number_matched AND number_matched > 0 THEN --need to have paging links

we check if we have needs for previous/next links. I believe there is a case that is missing (ref: https://github.com/stac-utils/stac-fastapi-pgstac/pull/155/files#r1910644543) when you can have less than limit number of collection (e.g n_collections=4 and limit=10) but user may have provided offset=.

Anytime there is an offset>0 I feel we should have a previous link

cc @bitner