As Nova's API is unified to os_compute_api, the API policies are also
updated to use this format, Horizon needs to use Nova policy enforce
rules in the codebase. This patch also update nova_policy.json using
oslo-config-generator for Nova policy file.
Co-Authored-By: Rob Cresswell <robert.cresswell@outlook.com>
Implements: blueprint update-nova-enforce-policies
Change-Id: Id7d01a39930c88592301a5035f0befe5293a78fa