Previously, we initialized the listeners on the order they were provided
to us on the config file. In the future, we'll want to add new listener
purposes that depend on existing ones, so the init order needs to be
deterministic.
With this change, we'll initialize components in this order:
1. gRPC Server for Controller API.
2. All `api` HTTP Servers & gRPC Gateway Muxes.
3. `cluster` gRPC Server.
This commit introduces some renames for the sake of clarity as well as
improved test coverage:
- Removes `gatewayMux` reference from Controller object. This object was
misleading and is now uneeded.
- Removed uneeded `context.Context` arguments.
- Separates gRPC Server and gRPC Gateway concerns, both in functionality
and in naming. These two were conflated before.
- Added unit tests on `startListeners`.
Hugo Vieira
b5ef468d33