Support for viewing MIVMIR, GICAM rank scores

[torbjorgen]

I'd like to have MIVMIR and GICAM scores visible in SCOUT similar to GENMOD rank score.

The relevant keys are:

- INFO/MivmirScore: float [0, 1]
    example: 0.98029

- INFO/MivmirExplanation: key-value dictionary str:float [-1,+1], can be mixed length in the future
    example: [most_severe_consequence=0.22,CADD=0.20,CSQ_MES-SWA_acceptor_alt=0.11,CSQ_MES-SWA_donor_alt=0.10, ... ]

- INFO/GicamScore: float [0, 1]
    example: 0.32022

Keys are only present for SNVs (not MT or SVs variants).