LDpred2: Add unit test for choice of reference alleles

[espenhgn]

(creating a separate issue for this, as #124 appears due to something else)

One potential issue could be if inconsistent choice of reference alleles in sumstats, LD file and genotype file isn't resolved correctly. To cover this with unit test it's possible to start with these scripts:
https://github.com/comorment/containers/blob/main/usecases/LDpred2/ldpred2_simulations.ipynb
and introduce random choice of reference alleles for genotype file (used for PRS computation), but also for the geno file used to perform GWAS . This can be done with plink:
plink --bfile <> --a1-allele <> --make-bed --out <>
just an idea...

Originally posted by @ofrei in #124 (comment)

[github-actions]

This issue appears to be stale due to non-activity