MIVMIR, GICAM add assert on missing annotation keys in VCF

[torbjorgen]

Make sure model throws error in case there are missing annotations that's required by the models.

Do the check on VCF header, not per variant (as annotations might be dropped depending on type).

This would make it easier to do integration and maintenance.

[torbjorgen]

I'm closing this story, as there's a request to make this model more flexible and usable outside of CG when the model goes into raredisease pipeline.

There are performance degradation in the model when running without SWEGEN_AF and Frq annotations, and this is documented in the raredisease pipeline docs nf-core/raredisease#812