Added the Radford Impurity Density model to the SSD extension

[bene73]

Until now, each detector was characterised by a constant impurity density. By using the Radford Impurity Density model, we can get a more realistic parametrisation of the detectors.

The impurity_density field now contains:

• name : "radford"
• params : The five resulting parameters from the fit, as well as the detector offset

This implementation introduces a new package dependency to LegendDataManagement, namely LsqFit.

[codecov]

Codecov Report

Attention: Patch coverage is 93.75000% with 1 line in your changes missing coverage. Please review.

Project coverage is 34.40%. Comparing base (7c834db) to head (6a31750).

Files with missing lines	Patch %	Lines
ext/LegendDataManagementSolidStateDetectorsExt.jl	93.75%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #72      +/-   ##
==========================================
+ Coverage   33.96%   34.40%   +0.43%     
==========================================
  Files          28       26       -2     
  Lines        1946     1959      +13     
==========================================
+ Hits          661      674      +13     
  Misses       1285     1285              

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[fhagemann]

@oschulz would you be ok with adding LsqFit as dependency until the fitted impurity density values make it into the metadata?

[fhagemann]

This would still need to be tested and done, I can take care of this

[fhagemann]

We also might wanna add a keyword argument such that the user can choose whether they want to use the RadfordImpurityDensity from the crystal metadata or not

[fhagemann]

I closed this by accident when trying to resolve the merge conflicts. Find the follow-up PR here: #74