Add additional functionality to IGV omit patterns for VCF/BAM/CRAM files

[mikkonie]

Nothing to see here yet, just a placeholder for a requested feature we'll need to discuss internally next week..

TODO:

• Define use case
• Define how required features differ from what is already implemented

[mikkonie]

Oops, I accidentally opened a dupe in #1923 and wrote a spec there. Closing this one.