`save_kmz`: support data in UTM

[Alex-Lewandowski]

Description of proposed changes

This addresses an issue causing improperly geocoded velocity kmz files from data in UTM. KML only natively supports WGS84, so I added code to convert the bounding box coordinates to WGS84 when necessary.

Reminders

• [x] Fix #1211
• [x] Pass Pre-commit check (green)
• [x] Pass Codacy code review (green)
• [x] Pass Circle CI test (green)
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• [x] If modifying functionality, describe changes to function behavior and arguments in a comment below the function declaration.
• [x] If adding new functionality, add a detailed description to the documentation and/or an example.

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