Handle VLM Network Requests/Responses (aggregate CAF retrieval)

[jsstevenson]

• Wrap AnyVar search functions. Perform against all contained nodes.
• Return CAF
• Add HTTP endpoint(s) wrapping the above, compliant with VLM API

[theferrit32]

https://va-spec.ga4gh.org/en/1.0/va-standard-profiles/base-profiles/study-result-profiles.html#cohort-allele-frequency-study-result

[theferrit32]

Gregor also has these INFO fields:

AC_HET 
AC_HOM
AC_HEMI