gnomad V4 update for small variants

[anjalijain22]

• Updated vcfanno config to point to gnomad v4 joint frequency annotation VCF
• Use this branch in conjunction with this cre branch Update column names for gnomad v4 update cre#63

[anjalijain22]

The issue with missing values in "gnomAD_fafmax_faf95_max" has now been addressed. These values are actually supposed to be zero as discussed on the gnomAD forum.

To include the variants with missing values, I have tweaked the crg2/wrappers/vcf2db/wrapper.py file which updates all NULL values to -1 for gnomad_fafmax_faf95_max column in the gemini DB. Detailed report comparisons can be found here: https://sickkidsca-my.sharepoint.com/:w:/r/personal/anjali_jain_sickkids_ca/_layouts/15/Doc.aspx?sourcedoc=%7BA8E732B2-DC5E-4D27-89BA-0D94F20ADE72%7D&file=gnomAD_v4.1_update.docx&action=default&mobileredirect=true

[Madelinehazel]

Excellent, made a couple of minor changes in the cre branch.