Refactor passing configuration to control plane service

[rampage644]

PR #280 introduced a way to pass certain configuration parameters to ControlPlaneImpl object. This approach is difficult to generalize, test and maintain.

Instead, it should follow Rust idiomatic approaches with either Builder pattern or new_with_opts (or something like this) constructor.

All configuration parameters should be defined declaratively and readable from either cli args or env (or in some future from configuration file). All components should be parametrizable via constructors only.

[eadgbear]

We shouldn't be using std::env anywhere in the crates. It should all be done by passing in config structures created by the bin/bucketd crate