Mapping refactor - use registered xarray accessor for mapping code

[subagonsouth]

Algorithm Description:

Investigate whether doing a refactor on some of the mapping code would benefit from using registered accessors instead of the class structure that has been implemented. For documentation and an example see:

https://docs.xarray.dev/en/stable/internals/extending-xarray.html

IMAP Hi Goodtimes accessor: Not yet merged see hi_goodtimes.py