Include Async API CLI

[rivancic]

There are two main Async API tools:

• First one is for managin Async API files -> https://github.com/asyncapi/cli
• Second one is just generator -> https://github.com/asyncapi/generator

In my case I am wrapping only a generator and for this reason has only a asyncApiGenerator task because it doesn't contain other functionality. While I may combine both the Async API CLI and Generator into one plugin and provide additional tasks like
https://www.asyncapi.com/docs/tools/cli/usage#asyncapi-bundle

It actually seems I can completely drop generator plugin and use CLI Only (Might Rename plugin to async api gradle)