Make it easy to test mapping/setting.json changes by adding an elasticsearch-setup:debug image to docker-compose.dev.yml

The overridden elasticsearch-setup container mounts the local mapping/setting.json files and uses them to create indices.
Followed the method used in the dev setup for gms/mae-consumer/mce-consumer containers

Test
./docker/dev.sh runs correctly and confirmed that the local changes to mappings got picked up
Running the prod path by doing the following (Thanks @jplaisted)

cd docker
./nuke.sh # start from scratch to really verify things
docker compose pull # pull latest images
docker image rm docker_elasticsearch-setup # delete pulled image
docker-compose build elasticsearch-setup # rebuild image
docker-compose -p datahub up # launch docker without pulling

ran correctly as well.

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable)