MAGFit: features to be implemented

Somewhere to note down all the features that we would like:

- [ ] Option to enter location manually (https://github.com/ArduPilot/WebTools/pull/61#issuecomment-1805684265)
- [ ] Use full WMM with date and altitude. https://www.ncei.noaa.gov/products/world-magnetic-model, https://www.npmjs.com/package/geomag
- [ ] Use position throughout flight rather than just using a single origin, this will make the results better for long range flights.
- [ ] Option to use GSF and GPS yaw as "truth"
- [ ] Add yaw on the flight data plot https://discuss.ardupilot.org/t/new-magfit-compass-calibration-webtool/110192/2
- [x] Hide "Motor compensation sources" plot if there are none. https://github.com/ArduPilot/WebTools/pull/96

No file, test, or entry point is named. Start by locating the MAGFit implementation, then review the linked pull request, WMM references, and discussion; completion would require agreeing on scope and implementing and verifying the selected unchecked features.

Written by the indexing model from the issue text.