deps: drop defusedxml

[yunjunz]

Description of proposed changes

• dependencies: revert replace xml.etree with defusedxml for ElementTree #340 back the ElementTree usage from defusedxml to the native xml.etree module, to drop this extra dependency, because there are only two use cases in the code: parse known XML files from ISCE and SNAP.

• delete add_attribute from setup.py and __main__.py, which was missed in plate_motion: add --plate option to use built-in tables #906

• objects.ionex.get_ionex_value(): turn ON rotate_tec_map by default

• cli.closure_phase_bias: add a link to the notebook (Tutorial for closure_phase_bias.py MintPy-tutorial#40) in the example usage.

Reminders

• Pass Pre-commit check (green)
• Pass Codacy code review (green)
• Pass Circle CI test (green)
• 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.