Add ward reduction

[m-bossart]

Outstanding issues:

• Accounting for virtual admittances in various PowerNetworkMatrix types
• Reassigning reference bus
• Improving performance of Z matrix computation
• Add tests for PTDF with ward reduced system

[github-actions]

Performance Results

Version	Precompile Time
Main	2.574634095
This Branch	2.496671016

Version	Execute Time
Main-Build PTDF First	5.941369873
Main-Build PTDF Second	0.090161161
Main-Build Ybus First	0.555091884
Main-Build Ybus Second	0.007686856
Main-Build LODF First	1.458539587
Main-Build LODF Second	0.375077436
This Branch-Build PTDF First	6.214990399
This Branch-Build PTDF Second	0.125586356
This Branch-Build Ybus First	0.565093298
This Branch-Build Ybus Second	0.008339496
This Branch-Build LODF First	1.244847195
This Branch-Build LODF Second	0.401261118

[codecov]

Codecov Report

Attention: Patch coverage is 95.00000% with 8 lines in your changes missing coverage. Please review.

Project coverage is 79.73%. Comparing base (7069dca) to head (c922a32).

Files with missing lines	Patch %	Lines
src/network_reduction.jl	76.19%	5 Missing ⚠️
src/radial_reduction.jl	71.42%	2 Missing ⚠️
src/lodf_calculations.jl	91.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #98      +/-   ##
==========================================
+ Coverage   77.61%   79.73%   +2.11%     
==========================================
  Files          14       16       +2     
  Lines        1398     1411      +13     
==========================================
+ Hits         1085     1125      +40     
+ Misses        313      286      -27     

Flag	Coverage Δ
unittests	79.73% <95.00%> (+2.11%)	⬆️

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

Files with missing lines	Coverage Δ
src/BA_ABA_matrices.jl	93.47% <100.00%> (-0.76%)	⬇️
src/adjacency_matrix.jl	73.91% <100.00%> (ø)
src/incedence_matrix.jl	81.25% <100.00%> (-3.75%)	⬇️
src/ptdf_calculations.jl	92.18% <100.00%> (-0.43%)	⬇️
src/serialization.jl	96.25% <ø> (ø)
src/virtual_lodf_calculations.jl	89.53% <100.00%> (-0.36%)	⬇️
src/virtual_ptdf_calculations.jl	87.50% <100.00%> (-0.15%)	⬇️
src/ward_reduction.jl	100.00% <100.00%> (ø)
src/ybus_calculations.jl	47.36% <100.00%> (+6.13%)	⬆️
src/lodf_calculations.jl	76.71% <91.66%> (-1.75%)	⬇️
... and 2 more

[github-actions]

[JuliaFormatter] _{reported by reviewdog 🐶}

Suggested change