add plan execution minutes pool with renewal refill support

[emma-sg]

Support for more flexible pricing plans, including yearly plans.

[SuaYoo]

The "plan" labeling is somewhat unclear to me since a subscription plan can be a monthly plan. Or is it that if it's a yearly subscription there is no monthly values returned and thus "Monthly Remaining"/"Used" won't be shown?

[emma-sg]

Or is it that if it's a yearly subscription there is no monthly values returned and thus "Monthly Remaining"/"Used" won't be shown?

@SuaYoo Yes, planExecMinutes is intended to supercede monthlyExecMinutes - the plan is to roll this out for yearly plans specifically, and then once that's been running without issue for a while we'll replace the existing plans that are tied to calendar months with versions that are instead tied to renewal dates.

[SuaYoo]

Yes, planExecMinutes is intended to supercede monthlyExecMinutes - the plan is to roll this out for yearly plans specifically, and then once that's been running without issue for a while we'll replace the existing plans that are tied to calendar months with versions that are instead tied to renewal dates.

Got it, in that case maybe a small deprecation notice/comment somewhere since that's not clear from the template right now?