OPSIM-1107 Documentation restructure

[rhiannonlynne]

Restructuring the documentation to work for the Rubin user guide. There are lots of ruff updates as well, to bring documentation lines into line length compliances and sometimes to update and improve the documentation too.

[rhiannonlynne]

This still isn't finished, but I'm running out of steam and will have to just make another ticket to finish ruff and docstrings in the remainder of the MAF module. It does make the rest a lot better though.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 41.72185% with 88 lines in your changes are missing coverage. Please review.

Project coverage is 58.31%. Comparing base (78851ce) to head (b263fb5). Report is 17 commits behind head on main.

Files	Patch %	Lines
...contrib/calculate_lsst_field_visibility_astropy.py	11.53%	23 Missing :warning:
.../lss_obs_strategy/galaxy_counts_metric_extended.py	14.28%	6 Missing :warning:
...s_strategy/galaxy_counts_with_pixel_calibration.py	0.00%	6 Missing :warning:
rubin_sim/maf/maf_contrib/star_counts/coords.py	0.00%	6 Missing :warning:
rubin_sim/maf/maps/create_gaia_density_map.py	0.00%	5 Missing :warning:
rubin_sim/phot_utils/sed.py	0.00%	5 Missing :warning:
rubin_sim/maf/maf_contrib/triplet_metric.py	0.00%	4 Missing :warning:
...ubin_sim/maf/maf_contrib/star_count_mass_metric.py	40.00%	3 Missing :warning:
rubin_sim/maf/maf_contrib/star_count_metric.py	50.00%	3 Missing :warning:
rubin_sim/maf/metrics/simple_metrics.py	75.00%	2 Missing and 1 partial :warning:
... and 17 more

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #387 +/- ## ========================================== + Coverage 55.25% 58.31% +3.05% ========================================== Files 305 295 -10 Lines 29681 28102 -1579 Branches 4285 3989 -296 ========================================== - Hits 16400 16387 -13 + Misses 12338 10770 -1568 - Partials 943 945 +2 ```

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