[Services] Use clap to provide configurable cli experience to blob service

Summary:
Blob service should be able to be configured through environment
variables and arguments. This enables this scenario for the grpc port and
localstack url.

https://linear.app/comm/issue/ENG-2310

Depends on D6463

Test Plan:

RUST_LOG=debug cargo run -- --port 50050 # should see aws config logic
sudo lsof -i -P | grep LISTEN | grep 50050 # should see process bound to port

Integration tests need additional work to test integration more thoroughly.

Reviewers: bartek, varun, max

Reviewed By: bartek

Subscribers: ashoat, tomek, atul

Differential Revision: https://phab.comm.dev/D6464