Code formatting cleanup

[alexgleith]

• Minor changes to code, like var is True rather than var == True.
• Changed to isinstance(filepath, S3File) rather than type(filepath) == S3File because my linter said that the latter wouldn't work (lead to unreachable code)

openjournals/joss-reviews#7025 (comment)

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[giswqs]

@alexgleith Thank you very much for the code cleanup. Some code blocks you pointed out were inherited from the EMIT-Data-Resources. I did not make changes.

https://github.com/nasa/EMIT-Data-Resources/blob/main/python/modules/emit_tools.py#L347

You suggested changes look good except the following:

ortho = True and ortho = False are intended for variable assignment, not conditional statements. So these need to be reverted.

[alexgleith]

Whoops, sorry about that mistake @giswqs!

Ok, that makes sense re. the EMIT code.

I'm a bit uncomfortable with this section, as it's not very safe, but it makes more sense if it was just like that in the upstream source.

    if longitude is not None and latitude is not None:
        ortho = True

    if downtrack is not None and crosstrack is not None:
        ortho = False

[giswqs]

The idea was to simplify the upstream code in the Exploring_EMIT_L2A_Reflectance.ipynb notebook by creating the plot_emit() function that can plot both orthorectified and non-rothorectified EMIT data. If both latitude and longitude are set, we assume it is orthorectified data. Otherwise, if both downtrack and crosstrack are set, we assume it is non-orthorectified data. Would this be acceptable? I am open to suggestions for improving it.

[giswqs]

I am merging this PR for now to avoid conflicts with a new PR also editing emit.py. I would be happy to improve this section if needed.