Civi::pipe - Define option `apiError`

Civi::pipe - Define option `apiError`

This option balances two interests:

- For generic plumbing code, it's easier to keep the API errors in their canonical format.
- For bespoke JSON-RPC client code, it's easier to bind errors into JSON-RPC errors. This way
  downstream clients can adapt the errors to their own convention (PHP exceptions, JS exceptions,
  promise-failures, ad nauseum)