pygmt.fitcircle: Find mean position and great [or small] circle fit to points on sphere

*This issue serves as the central place for discussing and tracking the implementation of the `fitcircle` method in PyGMT. The issue will be closed when the initial implementation is complete. Progress is tracked at https://github.com/orgs/GenericMappingTools/projects/3.*

## Documentation

- GMT: https://docs.generic-mapping-tools.org/dev/fitcircle.html
- GMT.jl: https://www.generic-mapping-tools.org/GMTjl_doc/documentation/modules/fitcircle
- PyGMT: https://www.pygmt.org/dev/api/generated/pygmt.fitcircle.html

## GMT Option Flags and Modifiers

☑️: *Implemented*; ⬜: *To be implemented/discussed*; ~~Strikethrough~~: *Won't implement*.

## GMT Option Flags and Modifiers

☑️: *Implemented*; ⬜: *To be implemented/discussed*; ~~Strikethrough~~: *Won't implement*.

- [ ] `table`:
- [ ] `-L`: `norm`
- [ ] `-F`
- [ ] `-S`: `small_circle`
- [ ] `-V`: `verbose`
- [ ] `-a`
- [ ] `-b`
- [ ] `-di`
- [ ] `-e`
- [ ] `-f`
- [ ] `-g`
- [ ] `-h`
- [ ] `-i`
- [ ] `-o`
- [ ] `-q`
- [ ] `-:`
- [ ] ~~`--PAR=value`~~: Use `pygmt.config()` instead

## Linked Pull Requests

- [x] Initial feature implementation #1550
- [ ] Add a tutorial or gallery example

## Related Issues and Discussions

*Add links to related wrapper discussions, API design threads, or upstream GMT changes here.*