Merge ApiStatus + ErrorResponse

[clux]

Follow up from #36
Currently Status and ErrorResponse are the same underlying object in kube AFAIKT, but are returned in different contexts:

• ErrorResponse when !request.is_success() (and you need to grab it out of the Error)
• Status when request.is_success() and is_right()

We should standardise this to reduce duplication.

[clux]

Edited this issue as ApiError was renamed to ErrorResponse when moving to thiserror.