Raster footprint: let user set destination CRS 4326

[jsignell]

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Related Issue(s): Closes #435

Notes:

• The output of the footprint method is still geojson, it's just invalid geojson if the user has declared a different dest crs. I am not sure if that is the right approach or not.
• I didn't update the deprecated functions. Don't see a reason to enable this enhancement on deprecated functions.
• I wrote a test, but I'd appreciate an extra set of eyes to make sure the expectation is sane. Or maybe there is a better way to test.

PR checklist:

• [x] Code is formatted (run scripts/format).
• [x] Code lints properly (run scripts/lint).
• [x] Tests pass (run scripts/test).
• [x] Documentation has been updated to reflect changes, if applicable.
• [x] Changes are added to the CHANGELOG.