Bind to VPC Services by name rather than service_id

[sodabrew]

Describe the solution

In commit 555a6da0fbda6e792264b59984687e336c179619 / PR #10647, VPC Services bindings were added by giving a binding name visible to the worker script and a service_id copied from the VPC Services page. The config stanza is:

"vpc_services": [
  { "binding": "NAME", "service_id": "a-b-c-1-2" }
]

This ticket is a request to allow { "binding": "NAME", "service": "name" } and let wrangler look up the service_id as an internal detail.

[sodabrew]

cc @efalcao @petebacondarwin