feat: Zero-ETL for PG

[TianyuZhang1214]

Resolves: #176, #119

Features Added:

1. CREATE SUBSCRIPTION Support

This PR introduces support for the CREATE SUBSCRIPTION SQL command in MyDuck Server. Users can now set up replication from a source PostgreSQL instance with the following SQL statement:

CREATE SUBSCRIPTION mysub CONNECTION 'dbname=foo host=bar user=repuser' PUBLICATION mypub;

Automatic Slot and Publication Creation:
If the required replication slot and publication are not already present on the source PostgreSQL server, they will be created automatically during the execution of the CREATE SUBSCRIPTION command.

---

2. Replica Mode with Docker

Added support for running MyDuck Server in replica mode, enabling seamless replication from a source PostgreSQL database at launch.

Usage Example:
The following docker run command demonstrates how to launch MyDuck Server in replica mode:

docker run \
  -p 3306:3306 \
  -p 5432:5432 \
  --privileged \
  --detach \
  --env SETUP_MODE=REPLICA \
  --env SOURCE_DSN="postgres://postgres:[email protected]:15432" \
  apecloud/myduckserver:latest

• SETUP_MODE=REPLICA: Configures MyDuck Server to function as a replica.
• SOURCE_DSN: Specifies the source PostgreSQL connection string.

This simplifies the process of setting up replication directly from a PostgreSQL database.

[fanyang01]

Looks exciting! This PR greatly simplifies the experience of Postgres replica setup.

A few comments:

[VWagen1989]

This is really an exciting feature that provisions an easy way to create a replication stream to PostgreSQL. It makes things simple, and as simple as possible is a good taste!
Here's my review comments.

[fanyang01]

Thanks! LGTM

[VWagen1989]

LGTM!