Add Support for Postgres in Document Store

[jainnidhi703]

Use Case

Adding an alternative datastore i.e. Postgres to the document store, currently, it is limited to MongoDB only.

Proposal

The entity document will be stored as json in Postgres data-store. Following the conventions from MongoDB,
the postgres schema will look as follows:

CREATE TABLE documents (
	id TEXT PRIMARY KEY,
	document JSONB NOT NULL,
	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
	updated_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
);

The document-store will connect to Postgres via JDBC driver.

I'm already working on a PR to add this. Here is the initial draft of the PR.
All the functionalities provided by MongoDB will be implemeneted on Postgres as well.

[JBAhire]

Thanks for initiating this @jainnidhi703 ! looking forward to it! :)

[kotharironak]

Closing this as above PR adds support for this.