feat: Add new function that creates an instance of a model with the option to skip validation

[pesap]

This PR adds a new method that creates an instance of a model but with the option skip the validation of pydantic by setting a skip_validation flag.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 93.33333% with 2 lines in your changes missing coverage. Please review.

Project coverage is 78.02%. Comparing base (05befac) to head (e2cb6e5).

Files with missing lines	Patch %	Lines
src/r2x/parser/reeds.py	87.50%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #110      +/-   ##
==========================================
+ Coverage   77.98%   78.02%   +0.03%     
==========================================
  Files          39       39              
  Lines        3865     3872       +7     
==========================================
+ Hits         3014     3021       +7     
  Misses        851      851              

Files with missing lines	Coverage Δ
src/r2x/parser/handler.py	85.71% <100.00%> (+0.75%)	⬆️
src/r2x/parser/reeds.py	91.25% <87.50%> (+0.02%)	⬆️

[jarry7]

• Seems like a bunch of changes/additions in the PR to enable validation flag. Just want to understand (at a high-level) what they are for? e.g. LoadZone, Reserve, TransmissionInterface (based on the new create_model_instance) and it just seems to be for enabling the model_validation flag.
• I would not be well positioned to decide whether it is comprehensive in coverage but can test for nodal functionality if that is what you would like? Perhaps @kodiobika would be best to test for functionality? Otherwise, have you done this already @pesap?
• I see all the checks have passed but was wanting to see whether the functionality is as you would expect (fundamentally - avoid validation)

[pesap]

At a high-level, every time we used to create an instance of a PSY model, we call this new function that allows to create a validated model or an un-validated model.

I included simple test of the function, should be enough to test that we can create a unvalidated model. See test_models.py