Use YANG modules to configure and operate OpenALTO

[fno2010]

The current OpenALTO is based on the INI-style configuration. But it should be conceptually equivalent to the YANG-based configuration.

We first need to convert the INI-style config to JSON-style.

Then we can use yangson to translate the YANG-based configuration to the JSON data schema and instance.

https://github.com/ietf-wg-alto/draft-ietf-alto-oam-yang/blob/main/yang/yang-library-ietf-alto.json provides a valid yang library definition.

[fno2010]

yangson is lightweight enough as a starting point, but it cannot separate config and operational datastores. Maybe sysrepo is a better choice.