Set Sponsor Discount Code to never expire

[kimwhite]

Is your feature request related to a problem? Please describe.
When the SPONSOR Membership Account is renewed auto or manually, they keep the same Sponsor Code with the same expiration date (1 year). So the code will no longer work after a year.

Describe the solution you'd like
Sponsor Codes should NEVER expire or at least be set to 10 years.
Sponsor Codes will become inactive when the SPONSOR expires or is canceled so an expiration date is not necessary.

Additional context
Until this is added, Site owners can use this code recipe to set the expiration date to 10 (or whatever you set it for) years. This will only apply to new checkouts. https://gist.github.com/andrewlimaza/7665340a1c127dfb7d1ab1907b86ffc7