Description of the problem

When using latlon2yx to convert a set lat/lon points to pixel coordinates when using a UTM-based dataset, latlon2yx calls latlon2utm. When latlon2utm performs its conversion, it always converts the lat/lon coordinate into the native UTM zone for that point. This is not the desired behavior in some cases, because UTM-based MintPy datasets are in a single UTM zone, even if they cross a UTM boundary.

Proposed Changes
Where appropriate, invoke the force_zone_number/letter arguments of the utm package's from_latlon function to ensure coordinates are converted correctly.