Better configuration via Bedrock

[mdorier]

Right now the Mobject client gets the list of server addresses from an SSG file. It then assumes that the Mobject provider has provider id of 1. We need to rely on Bedrock to find out the provider ids. This can be done in two ways:

• Either the client uses the Bedrock client library to query the Bedrock deployment (introduces a dependency on Bedrock for the client);
• Or we can make a Jx9 script for Bedrock, use bedrock-query to get the provider ids from Bedrock, and make the client expect the result of this query (introduces a dependency on a Json library for the client and makes deployment a multi-step process).