Add oslopolicy-convert-json-to-yaml tool

Add ``oslopolicy-convert-json-to-yaml`` tool which can be
used to convert the json formatted policy file to yaml format.
It takes json formatted policy file as input and convert it to
a yaml formatted policy file similar to 'oslopolicy-sample-generator'
tool except keeping the overridden rule as uncommented.

This tool does the following:

* Comment out any rules that match the default from policy-in-code.
* Keep rules uncommented if rule is overridden.
* Does not auto add the deprecated rules in the file unless it not already
  present in the file.
* Keep any extra rules or already exist deprecated rules uncommented
  but at the end of the file with a warning text.

I did not add the new functionality in existing 'oslopolicy-policy-upgrade'
tool because the above listed features of new tool end up creating a
complete different code path instead of reusing it from existing tool so it
better to have separate tool which can be removed in future once all deployments
are migrated to YAML formatted file.

This commits add doc and reno also for this tool

Partial implement blueprint policy-json-to-yaml

Change-Id: Icc245951b2992cc09a891516ffd14f3d4c009920

1 files changed, 5 insertions, 0 deletions

diff --git a/releasenotes/notes/add-policy-convert-json-to-yaml-tool-3c93604aee79f58a.yaml b/releasenotes/notes/add-policy-convert-json-to-yaml-tool-3c93604aee79f58a.yaml
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+---
+features:
+  - |
+    Add ``oslopolicy-convert-json-to-yaml`` tool to convert the json formatted
+    policy file to yaml format in compatible way. Refer to `this document <https://docs.openstack.org/oslo.policy/latest/cli/oslopolicy-convert-json-to-yaml.html>`_ for details.