Deprecate ZeebeREST client, create C8REST client

[jwulf]

The new REST API is a unified one.

[jwulf]

We'll support the experimental methods in another spike.

[jwulf]

I'm using a SNAPSHOT build of Zeebe with alpha-5 builds of 8.6 and I seem to have most of the REST methods available for testing.

I'm taking the opportunity to also add a pluggable logging framework into the SDK.

This will not be retrofitted to the existing cilents, but for the new C8 REST client, it will come with a default Winston logger, and the ability for users to inject their own winston logger instances.