Add generation rate to Sesame PDD output

[phoebe-p]

The generation rate G, calculated using the incident spectrum and whichever optical solver method is selected, is used by the PDD solver but there is currently no convenient way for the user to access it - they instead need to access the wavelength-dependent generation rate and integrate this manually with the incident spectrum. This adds the generation rate G in a junction to the outputs of the Sesame drift-diffusion solver easily accessible by the user after a calculation.

Also fix some unrelated issues relating to Boost library causing GitHub Actions tests for M1 Macs to fail.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 60.35%. Comparing base (32311b3) to head (52c3e85).
Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
solcore/sesame_drift_diffusion/solve_pdd.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #286      +/-   ##
===========================================
+ Coverage    60.24%   60.35%   +0.11%     
===========================================
  Files          108      108              
  Lines        12358    12388      +30     
===========================================
+ Hits          7445     7477      +32     
+ Misses        4913     4911       -2     

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