fix: don't limit footprint points, increase capture area buffer TDE-1049

[amfage]

Motivation

The default behaviour of gdal_footprint is to set a maximum limit of 100 points in each footprint. This is not enough for all tiles, resulting in some gaps between tiles and not enough detail on more complicated shapes. The solution is to allow unlimited points in tile footprints, and to increase the buffer distance used when simplifying the capture area.

A buffer size of 2 * gsd was chosen after some investigation, recorded in TDE-1049. The aim is to reduce the number of vertices and therefore the file size, while still describing the capture area in enough detail.

Modification

• gdal_footprint use the -max_points unlimited option
• Set the capture area to use 2 * gsd for the buffer distance.

Checklist

If not applicable, provide explanation of why.

• Tests updated
• Docs updated
• Issue linked in Title