Description of proposed changes

This PR adds the example GMTSAR datasets for MintPy inputs, as prepared by @Xiaohua-Eric-Xu.

• docs: add SanFranBaySenD42 for GMTSAR

  • add docs/templates/SanFranBaySenD42.txt for GMTSAR
  • demo_dataset.md: add SanFranBaySenD42 for GMTSAR with figure (with DOI from zenodo)
  • use demo fig from github/insarlab/design-doc repo, instead of Yunjun's obsolete personal website, for better independency.

• tests: add GMTSAR into the regular circle ci testing using example dataset from zenodo

  • add tests/configs/SanFranBaySenD42.txt
  • tests/smallbaselineApp.py: add SanFranBaySenD42 dataset with a false URL for place holder
  • add SanFranBaySenD42 to the regular Circle CI integration testing

• load water mask for gmtsar, by adding:

  • objects.stackDict.geometryDict.write2hdf5(): convert NaN value to zero.
  • prep_gmtsar.prepare_geometry(): add all supported geometry data files, including water mask file
  • prep_gmtsar: add comments on input/output parameters for all functions.

• utils.readfile._attribute_gmtsar2roipac: bugfix for ORBIT_DIRECTION

Reminders

• Pass Pre-commit check (green)
• Pass Codacy code review (green)
• Pass Circle CI test (green)
• Pass local test
• Make sure that your code follows our style. Use the other functions/files as a basis.
• If modifying functionality, describe changes to function behavior and arguments in a comment below the function declaration.
• If adding new functionality, add a detailed description to the documentation and/or an example.