Adds conversion between material depth and attenuation

[Matt-Carre]

Fixes #2041
Adds tests and functions to convert between depth (measured in cm) and attenuation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.13%. Comparing base (0f2534c) to head (68566cd).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2049   +/-   ##
=======================================
  Coverage   99.13%   99.13%           
=======================================
  Files         337      337           
  Lines       13079    13096   +17     
=======================================
+ Hits        12966    12983   +17     
  Misses        113      113           

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[oliwenmandiamond]

The standard for dodal for tests is "mirror the file structure of the src folder with the corresponding code files. Use the test_*.py naming convention for test files."

You have created many test files that don't mirror the src structure e.g test_photon_mass_attenutation.py, test_thickness_required_to_attenuate.py etc.

Can you please update your tests accordingly?

https://diamondlightsource.github.io/dodal/main/how-to/write-tests.html

[Matt-Carre]

Currently, what I have works, but I could create a second model to check if the absorption coefficient is greater than 1.0e-14 with pydantic as well. Worth doing? Or do we want it to raise that specific value error?