Fix missing JEFF-4.0 directory-structure TSL PuO2, ThO2, UO2, Zy4

[yrrepy]

This PR adds the "directory-structure" S(α,β) evaluations from JEFF-4.0 that are currently missed in processing:

• Refactor thermal processing so that directory-based evaluations can use the existing process_thermal() workflow.
• Supply the material metadata needed to process the directory-based evaluations correctly.
• Preserve the eight Zircaloy-4 burnup states as separate tables: 10-80 GWd/t
• Process Zircaloy-4 using the NJOY-generated ACE elastic data, preserving the mixed-elastic Sum representation for Sn-115, Sn-117, Sn-119, and Zr-91, including both coherent and incoherent elastic cross sections and distributions.

Affected TSL:

• tsl_PuO2

  • tsl_O16_PuO2
  • tsl_Pu238_PuO2
  • tsl_Pu239_PuO2
  • tsl_Pu240_PuO2
  • tsl_Pu241_PuO2
  • tsl_Pu242_PuO2

• tsl_ThO2

  • tsl_O16_ThO2
  • tsl_Th232_ThO2

• tsl_UO2

  • tsl_O16_UO2
  • tsl_U238_UO2

• tsl_Zy4

  • tsl_Sn112_Zy4
  • tsl_Sn114_Zy4
  • tsl_Sn115_Zy4
  • tsl_Sn116_Zy4
  • tsl_Sn117_Zy4
  • tsl_Sn118_Zy4
  • tsl_Sn119_Zy4
  • tsl_Sn120_Zy4
  • tsl_Sn122_Zy4
  • tsl_Sn124_Zy4
  • tsl_Zr90_Zy4
  • tsl_Zr91_Zy4
  • tsl_Zr92_Zy4
  • tsl_Zr94_Zy4
  • tsl_Zr96_Zy4

tsl_Zy4 has Burnup dependent files, structured as:

• c_Sn112_in_Zy4_10GWdt
• c_Zr91_in_Zy4_40GWdt
• c_Zr96_in_Zy4_80GWdt