Support an array data type for contact properties.

We are using Mailjet to contact customers of our software. We need to message different segments of customers based on which features they subscribe to (or which permissions a user has). Because of the numbers of features/permissions and the ongoing addition of new ones, it isn't particularly viable to map this to a series of boolean contact properties.

If you natively supported an array/list data type, that's what we'd ideally use to store this information, and then set up segments accordingly. The most obvious comparison operators I can foresee wanting to use for filters are:
- Contains
- Does not contain
- Contains any of
- Does not contain any of
- Contains all of
- Does not contains all of