Compute solid earth tide correction, add layer

[scottstanie]

• Here's a start: https://gist.github.com/scottstanie/d83654607b20589846f154d3a4390a2c . it used the COMPASS code without changing to radar coordinates.
• you'll need to get the geometry files, they should be in the geometry_dir = out_dir / "geometry", but we aren't currently passing those through.
• follow the other correction examples, like the ionosphere one here
• if possible, please also fix this docstring to be more descriptive about what the output files are

[scottstanie]

SET layer closed by #134, the geometry improvements are forthcoming