ob_tran detection of angular units in inverse direction

[snowman2]

From: https://github.com/pytroll/pyresample/issues/527

Related:

• https://github.com/OSGeo/PROJ/issues/1525
• https://github.com/OSGeo/PROJ/pull/1526

Example of problem

PJ* pj = proj_create(nullptr, "+proj=ob_tran +o_proj=longlat +o_lon_p=0 +o_lat_p=39.25 +lon_0=18 +datum=WGS84 +no_defs");
proj_angular_input(pj, PJ_FWD); // 1
proj_angular_input(pj, PJ_INV); // 0

Problem description

pyproj relies upon proj_angular_input to determine whether the input data needs to be cast to radians before and after transformations. Currently, it is not detecting radians are needed for this case of ob_tran in the inverse direction.

Expected Output

Currently seeking guidance.

Environment Information

• PROJ version: 9.2.1
• Operation System Information: Ubuntu 22

Installation method

• conda