Codegen more client.go files

[richardm-stripe]

Codegens nine more client.go files.

All changes except for two are formatting/ordering/variable naming/docstring changes that have no behavior effect.

Those two are:

• I replaced one errors.New(...) with fmt.Errorf(...) -- shouldn't make a difference -- these functions behave essentially identically
• In usagerecordsummary/client.go I move the assignment of path := ... outside of the inner Iter to be consistent with how the other Iter methods are written. This is technically a behavior change: with the previous code, if you mutated listParams.SubscriptionID halfway through pagination, things would switch to making requests on a different subscription -- in the new code mutating listParams will have no effect. I can't imagine anybody actually desires the old behavior.