Add capsid gene region for CAI drug class

[CBeelen]

Since HIVdb 9.2, there is a new drug class: Capsid inhibitors, CAI. We will be ignoring this drug class in MiCall release 7.16, because it's not currently relevant for the centre, and there are no scores yet in HIVdb 9.4 - only comments.
To make MiCall evaluate CAI resistance, do the following:

• Stop ignoring the CA gene region
• Define the capsid gene region in the projects and landmark_references.yaml: it is a part of gag, and it's also called p24.
• Make sure that the get_algorithm_regions method in resistance.py assigns the correct region to CA.