read_gdal: switch back to gdal kwargs to leverage its subsetting capability

[scottstanie]

Description of proposed changes

general quality-of-life fixes that came up while adding more GPS comparisons for UTM products (these are before those additions, it just because a big enough PR to submit)

• Typos/unused import fixes that were highlighted by my spellchecker
• Starting the use again of the subsetting capability of ReadAsArray instead of reading everything (utils: refactor time_func.py and add s1_utils.py  #661), since the errors in the comment were from this: ds.ReadAsArray errors when xoff, yoff are numpy.int64 OSGeo/gdal#8026 (but can be avoided by casting to a python numeric type)
• simplify logic in update_attribute_or_not to exit early
• backwards compatible changes to readfile functions to allow more functions to accept pathlib.Paths

Reminders

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• 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.

[yunjunz]

Looks all good to me, thank you @scottstanie!