Feat: Add a uniform diameter model and deprecate the 'radius' parameter

[adrien-berchet]

Description

The 'radius' parameter is used as default diameter value when we add sections but it's supposed to overwritten by the NeuronGrower._diametrize method, so we can just use an internal default value. Nevertheless, in some specific cases the diametrizer does nothing (that's actually the case in many tests), which I think is a bit weird. But to reproduce this behavior if someone needs it I added a uniform model which can take a diameter value and apply it to the entire neurites.

Checklist

This pull request is:

• A documentation / typographical error fix
  • Good to go, no issue or tests are needed
• A short code fix
  • Please include: Fixes: #<issue number> in the description if it solves an existing issue
    (which must include a complete example of the issue).
  • Please include tests that fail with the main branch and pass with the provided fix.
• A new feature implementation or update an existing feature
  • Please include: Fixes: #<issue number> in the description if it solves an existing issue
    (which must include a complete example of the feature).
  • Please include tests that cover every lines of the new/updated feature.
  • Please update the documentation to describe the new/updated feature.

[codecov]

Codecov Report

Merging #85 (1f25229) into main (ed9f4f0) will decrease coverage by 0.08%.
The diff coverage is 89.47%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #85      +/-   ##
==========================================
- Coverage   97.69%   97.62%   -0.08%     
==========================================
  Files          39       39              
  Lines        2172     2191      +19     
  Branches      375      381       +6     
==========================================
+ Hits         2122     2139      +17     
- Misses         30       31       +1     
- Partials       20       21       +1     

Flag	Coverage Δ
pytest	97.62% <89.47%> (-0.08%)	⬇️

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Files Changed	Coverage Δ
neurots/generate/diametrizer.py	98.74% <75.00%> (-1.26%)	⬇️
neurots/generate/tree.py	99.00% <100.00%> (+0.03%)	⬆️
neurots/preprocess/validity_checkers.py	100.00% <100.00%> (ø)