fix(plans): update plans with public API
fix(plans): update plans with public API

Zone Plans are now Zone Rate Plans. Update all types and methods to use
the new name.

Plans can now contain components, so add a new (private) type used in
the ZoneRatePlan type.

The Plan Details endpoint has gone, so remove this method.

BREAKING CHANGE: this changes and removes public types and methods.
Users of the library should adjust their code as follows:

types:
ZonePlan -> ZoneRatePlan
AvailableZonePlansResponse -> AvailableZoneRatePlansResponse
ZonePlanResponse -> ZoneRatePlanResponse

methods:
ZoneSetPlan -> ZoneSetRatePlan
AvailableZonePlans -> AvailableZoneRatePlans

ZonePlanDetails has been removed entirely.

cloudflare/cloudflare-go,cloudflare/cloudflare-go