FIX: Set emissivity value in surface material

[Samuelopez-ansys]

Close #4997

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.47%. Comparing base (8fbfdaf) to head (d924cb8).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5015      +/-   ##
==========================================
- Coverage   83.48%   83.47%   -0.01%     
==========================================
  Files         121      121              
  Lines       54868    54868              
==========================================
- Hits        45806    45802       -4     
- Misses       9062     9066       +4