Define a common VCF header

[mwalker174]

It's going above and beyond but it strikes me that we repeat a bunch of these header strings around the codebase a bunch and it would be pretty handy to put them into an svtk module somewhere similar to how we have GATKVCFHeaderLines and GATKSVVCFHeaderLines in the gatk repo. Then we could just easily set up a method or little loop to add all the standard lines in places like this where we want to create a VCF from scratch.

Originally posted by @cwhelan in https://github.com/broadinstitute/gatk-sv/pull/346#discussion_r892693033