read/load support for `isce2/alos2App` dense offset

[yunjunz]

Description of proposed changes

• utils.readfile.auto_no_data_value(): support alos2App dense offset

• utils.readfile.get_slice_list(): alos2App use rg/az order, instead of az/rg order in other isce2 applications.

• utils.isce_utils.extract_alosStack_metadata/extract_image_size_alosStack(): support geometry files from alos2App/dense_offset, which have different naming conventions as the ones from InSAR.

• load_data: use absolute path for better robustness

Reminders

• [x] Pass Pre-commit check (green)
• [x] Pass Codacy code review (green)
• [x] Pass Circle CI test (green)
• [x] Make sure that your code follows our style. Use the other functions/files as a basis.
• [x] If modifying functionality, describe changes to function behavior and arguments in a comment below the function declaration.