Refresh LGIrrep .jld2 files

[thchr]

I.e. run build/write_littlegroup_irreps_from_ISOTROPY.jl and save & commit new .jld2 files.

Use the new ISOTROPY dataset, which includes the fix for space group 214 (and then remove the method manually_fixed_lgir in build/parse_isotropy_ir.jl); see the https://github.com/thchr/Crystalline.jl/tree/update-isotropy-dataset branch that already takes some steps in this direction.

[thchr]

Another good reason to do this is that it would probably fix the persistent .git issues with CRLF detection of these files.
Might as well also remove data/lgirreps/irrepmatrices.jld2 when do this; not used for anything right now.

[thchr]

This is pretty much done, except for switching over to the new ISOTROPY dataset. There's not a lot of urgency to do that though; the data files had a lot of churn due to formatting changes etc., and while they still seem to work fine, there's no real point in doing it when we have a manual fix for SG 214 already.
Maybe worth doing if we ever get around to pulling the data files out into a separate repository.