EPIC | Authentication v1

[maxyu1115]

The core memas server does not contain any authentication, it trusts whoever the requester claims they are. (The namespace_pathname aka user_name)

This is mostly intended for now; MeMaS is not a user facing application, and we leave it up to developers to set up authentication for now.

However, we do need to implement/enable some basic authentications:

1. Make MeMaS support API key authentication.
2. Add support for authenticating to our dependency services (ES/cassandra/milvus). Right now we have very sus configs like xpack.security.enabled=false lol

TRACKS: #23, #24