A.17.1. Abstract Test for Requirement JPEG map content (Abstract test A.56)

[jiann]

[LibbyShihh]

test URL : https://test.cubewerx.com/cubewerx/cubeserv/demo/ogcapi/EuroRegionalMap

[LibbyShihh]

Aligned with the update in #58 , this test now compares maps at the same scale with different centers (no longer different scales).

[LibbyShihh]

Applied the same optimization as #58 (comment) : shifted the two map centers closer together (from 25%/75% to 35%/65% of extent width) so that the two maps partially overlap (~40%), making it easier to visually compare shared features.