[Feature Request]: Add support for running DSAdmin with Docker setup

[AFZL210]

Is your feature request related to a problem? Please describe.

DSAdmin provides a UI for viewing Google Cloud Datastore Emulator data when running the dev server. This is really useful, as we can quickly check whether data is updated or not. Currently, we can use DSAdmin with python setup easily, but with Docker we don't have a command that sets up all the necessary things for us.

Describe the solution (or solutions) you'd like

Add support for running DSAdmin with a Docker setup, just like we have other easy to use commands for running tests, viewing logs etc.

Describe alternatives you've considered and rejected

N/A

Additional context

Learn more about DSAdmin: https://github.com/oppia/oppia/wiki/Debugging-datastore-locally

[gp201]

Follow the steps below to run DSadmin

1. Delete the existing oppia-cloud-datastore container.
2. add

ports:
      - "8080:8080"

below the line

oppia/docker-compose.yml

Lines 84 to 88 in 6345bf8

	datastore:
	build:
	context: .
	dockerfile: ./docker/Dockerfile.backend
	container_name: oppia-cloud-datastore

3. Run make run-devserver
5. Run make shell.oppia-cloud-datastore, a terminal session within the docker container (oppia-cloud-datastore) should spawn.
6. Run cd ..
7. Download an archive for linux-amd64 from the DSAdmin releases GitHub page using wget. example (wget https://github.com/remko/dsadmin/releases/download/v0.20.0/dsadmin-v0.20.0-linux-amd64.tar.gz)
8. unzip the file using tar -xvf <tar_file>
9. Run ../dsadmin --project=dev-project-id --datastore-emulator-host=localhost:8089
10. open http://localhost:8080/ in a browser.

[gp201]

@AFZL210, can you confirm whether this fixes your issue?