Jd/fix reduction indexing

[jd-lara]

This PR add and error throw in cases where the user provides an external PTDF matrix with reduced branches and doesn't specify the option in the network model

[github-actions]

Performance Results

Version	Precompile Time
Main	4.130359424
This Branch	4.183276478

Version	Build Time
Main-Build Time Precompile	67.055589
Main-Build Time Postcompile	0.987157664
This Branch-Build Time Precompile	67.540807748
This Branch-Build Time Postcompile	0.988865308

Version	Build Time
Main-Solve Time Precompile	460.706950278
Main-Solve Time Postcompile	424.881551864
This Branch-Solve Time Precompile	1924.685989911
This Branch-Solve Time Postcompile	1881.23778164

[codecov]

Codecov Report

Attention: Patch coverage is 92.85714% with 1 line in your changes missing coverage. Please review.

Project coverage is 77.32%. Comparing base (5772e25) to head (4e2dfae).
Report is 33 commits behind head on main.

Files with missing lines	Patch %	Lines
src/core/network_model.jl	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1210      +/-   ##
==========================================
+ Coverage   77.24%   77.32%   +0.07%     
==========================================
  Files         121      121              
  Lines       13446    13458      +12     
==========================================
+ Hits        10387    10406      +19     
+ Misses       3059     3052       -7     

Flag	Coverage Δ
unittests	77.32% <92.85%> (+0.07%)	⬆️

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

Files with missing lines	Coverage Δ
...devices_models/devices/common/add_to_expression.jl	74.22% <100.00%> (+0.36%)	⬆️
src/core/network_model.jl	85.54% <50.00%> (-0.88%)	⬇️

... and 6 files with indirect coverage changes