Check rescue_server action attributes of Nova APIs

This patch adds the JSON schema for Nova V2 & V3 rescue server
action APIs response and validate the response with added JSON schema
to block the backward incompatibility change in the future.

For V3 API, "admin_password" in response body is depend on config
variable "enable_instance_password". So schema and request
is adjusted accordingly.
NOTE - V2 rescue API's response does not on above config variable.

The response body of rescue server V2 APIs is below:
{
    "adminPass": "%(password)s"
}

The response body of rescue server V3 APIs is below:
If CONF.enable_instance_password is true-
{
    "admin_password": "%(password)s"
}
Else
    {}

Partially implements blueprint nova-api-attribute-test

Change-Id: I85f18eaa58bfef1871100816f97487f9fa9bc0ee
Merge "Check rescue_server action attributes of Nova APIs"