Hard to maintain API schemas for schedulers

[Ken'ichi Ohmichi]

The API parameter scheduler-hints is used on "create a server" API,
and available parameters(same_host, different_host, etc.) depends on
available schedulers on each cloud.

In addition, the API definitions of scheduler-hints was written at a
single place, and it was hard to maintain it because we needed to check
an API definition from different scheduler module file.
For easy maintenance, it is necessary to migrate API definitions to the
corresponding scheduler modules.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/220891

[OpenStack Infra (hudson-openstack)]

Change abandoned by Ken'ichi Ohmichi (<email address hidden>) on branch: master
Review: https://review.openstack.org/220440
Reason: Thanks for reviewing, but this patch is very premature and it is not essential because v2.1 API allows additional scheduler-hints parameters now.

at least, this feature will be useful after implementing JSON-Home.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Ken'ichi Ohmichi (<email address hidden>) on branch: master
Review: https://review.openstack.org/220891