DI framework for micro-service pattern within the Coder monolith

[cli/server.go](https://github.com/coder/coder/blob/main/cli/server.go#L317-L317) currently performs server initialization in a largely linear sequence with implicit dependencies between subsystems. As the Coder server has grown, this pattern has become harder to reason about and maintain.

Ideally we create a services DAG for startup & shutdown in the right order. A DI framework can be passed around for services to reference each other.