refs https://github.com/TryGhost/Team/issues/1727
- adds alpha feature flag for expiring comped subs
- adds duration to complimentary subs to set expiry
- shows details for expiring comped subs
refs: https://github.com/TryGhost/Team/issues/1145
- this should allow us to remove the /products endpoint in v5
It avoids:
- `kg-product-card`, that really is meant to say product
- `product-cadence` on offers
Co-authored-by: Rishabh <zrishabhgarg@gmail.com>