[NixFifty] Gift Upgrades 2.4.2

• Only inject User Essentials templates if that add-on is active.

• Allow recurring upgrades to be gifted. The first term will be paid for by the gifter and the giftee can choose to renew upon its expiration.
• Expose Recent Gift Post's widget date limit as a configurable option.
• Add missing relation to the UserUpgradeExpired entity.
• Fix potential issues surrounding the giving of free gifts.