fix(dui3): ensures we don't override structure layers

[didimitrie]

where there's two materials of the same type in the same type, they would override each other; nevertheless, having two plywood layers for one wall is totally acceptable.

note: this is a poc solution for now, as i envision the whole parameter extractor stuff to be properly typed out.

[linear]

CNX-649 Assembly Structure - Two layers with the same material name not exported

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 8.40%. Comparing base (6e56c3c) to head (dd17d36).
Report is 2 commits behind head on dev.

Files with missing lines	Patch %	Lines
...tShared/ToSpeckle/Parameters/ParameterExtractor.cs	0.00%	2 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##             dev    #307      +/-   ##
========================================
- Coverage   8.41%   8.40%   -0.01%     
========================================
  Files        240     240              
  Lines       4815    4816       +1     
  Branches     556     556              
========================================
  Hits         405     405              
- Misses      4393    4394       +1     
  Partials      17      17              

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