feat: create memgpt server with postgres DB with docker compose up

[sarahwooders]

Please describe the purpose of this pull request.
This PR allows developers to run a memgpt service with docker compose up.

The service is configured by the following environment variables (can be set in a .env file):

MEMGPT_PG_DB=memgpt
MEMGPT_PG_USER=memgpt
MEMGPT_PG_PASSWORD=memgpt
MEMGPT_SERVER_PASS=test_server_token

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[cpacker]

LGTM!