Move PostgreSQL dockerfile to separate repository with automation for publishing or sibedge/postgres-plv8 docker image instead

[Konard]

We should move https://github.com/deep-foundation/deeplinks/blob/deeplinks-70-menzorg/postgresql/dockerfile to separate file.

This docker image was done when deep-foundation/deeplinks#70 was in progress, and this docker image now is published in deepf account of DockerHub and used in https://github.com/deep-foundation/hasura repository.

Or we should use existing https://hub.docker.com/r/sibedge/postgres-plv8 docker image or other compatible one.

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Forked from deep-foundation/deeplinks#340 by https://github.com/konard/gh-org-migrator