Add missing docstrings, update to Documenter 1.7, format markdown files

[kdayday]

• Update from Documenter 0.27 to 1.7
• Adds markdown files to formatter script and runs the formatter
• Resolves ~250 missing docstrings in APIs
  • add internal API for non-exported functions
  • Exports LowerBoundValueParameter, CostFunctionParameter, PieceWiseLinearCostVariable, HVDCLossesAbsoluteValue, which were in the public API but not exported
  • Add multiple missing pages/section to public.md, switch some things to autodocs
  • Automate table of contents

Closes #520

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.33%. Comparing base (dd26d5a) to head (98b1aa7).
Report is 20 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1143      +/-   ##
==========================================
+ Coverage   77.93%   78.33%   +0.39%     
==========================================
  Files         118      121       +3     
  Lines       12707    12723      +16     
==========================================
+ Hits         9903     9966      +63     
+ Misses       2804     2757      -47     

Flag	Coverage Δ
unittests	78.33% <ø> (+0.39%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
src/PowerSimulations.jl	100.00% <ø> (ø)
src/core/formulations.jl	96.87% <ø> (ø)
...itial_conditions/initial_condition_chronologies.jl	100.00% <ø> (ø)
src/operation/emulation_model_store.jl	80.48% <ø> (ø)
src/simulation/optimization_output_cache.jl	93.84% <ø> (ø)
src/simulation/optimization_output_caches.jl	95.45% <ø> (ø)
src/simulation/simulation.jl	82.94% <ø> (ø)
src/simulation/simulation_results.jl	87.91% <ø> (ø)
src/simulation/simulation_sequence.jl	91.26% <ø> (+7.93%)	⬆️

... and 13 files with indirect coverage changes