validate extension with json schema

[sambhavgupta0705]

This issue is a part of AsyncAPImentorship program #78

Main Objective

As part of the Mentorship program we need to validate the extensions with json schema.
A folder named extensions would be added just as bindings are present.

Description

#280
In brief, An extension enables the description of functionality or protocol related features. Everyone can create their own extensions to give users more freedom on the spec.

We need to have a JSON Schema validation. In fact, to enable validation in the parser, we need JSON Schema for AsyncAPI to contain JSON Schemas of individual extensions.

The final objective is to have a catalog of extensions that users can browse and use. Then, as time goes by, we enhance the catalog according to the demands / needs.

cc: @derberg

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[derberg]

do we really need a new issue, the one #280 is clear, specifies what will be changed, there were no objections. So I do not see a need for new issue, we just need a PR 😄

[sambhavgupta0705]

ok then I am closing this one