Currently project_id is allowed in request body
for all request, however, its not honered since project_id
is pulled from headers.
This commit separates the need for project_id only where
its needed. For instance, in users we expect project_id
to allow creating users for different projects or we
expect project_id in response body.
Partial-Bug: 1666695
Change-Id: Ie5fac9ef4c305ff7e67fe32855ca8100a8adfa82
9ddf2c4cd5