Include spherical ice-crystal optical properties in ga9 spectral files

[mo-jmanners]

Optical properties for spherical ice-crystals can be generated in the existing examples/ice_crystals/run_2022 script. Here these are added to the standard ga9 and ga9_ref files for research use.

[james-bruten-mo]

[Automatic Update]

The Code Review deadline for the Spring 2026 has passed. As this issue does not have a linked pull request it has been removed from the milestone. Please review this issue and either select a new milestone or close it as appropriate. Please contact @MetOffice/ssdteam if you think there has been an error.

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