cloudcommerceprocurement: add v1 API manually

cloudcommerceprocurement is not in https://www.googleapis.com/discovery/v1/apis.
Until it is, generating it manually and sticking it in this repository is a good
way to unblock customers that need it.

Change-Id: Iac31781b566a4c133c6911962dd53c198414f963
Reviewed-on: https://code-review.googlesource.com/c/google-api-go-client/+/47510
Reviewed-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Noah Dietz <ndietz@google.com>

Author: jeanbza