Initialize the database automatically when starting mquery

[msm-cert]

Currently the installation procedure is:

docker compose up --scale daemon=3  # this will take a while
docker compose exec web python3 -m mquery.db

Web container should initialize the database (run migrations) automatically.

This should happen when the web container is started.

Also update the documentation (remove the initialization step when it's not needed).

[msm-cert]

This overlaps a bit with #412

Some hints how to do it:

1. executing mquery.db is actually not the best solution here, just alembic upgrade head would be better. See teste2e:

      - name: run web with docker compose
        run: docker compose up --build -d web --wait
      - name: init the database
        run: docker compose exec -it -w /usr/src/app/src/ web alembic upgrade head
      - name: run the rest of the code
        run: docker compose up -d

2. But we want to remove this line altogether. You can google for something like "fastapi automatic alembic migrations" etc. One of the resutls: https://stackoverflow.com/questions/77170361/running-alembic-migrations-on-fastapi-startup

3. You can also take a look at how mwdb does it:
   https://github.com/CERT-Polska/mwdb-core/blob/d593f697ebf37e036e778641038d5613ed852a5f/docker/start.sh#L10
   https://github.com/CERT-Polska/mwdb-core/blob/d593f697ebf37e036e778641038d5613ed852a5f/mwdb/cli/cli.py#L60
   https://github.com/CERT-Polska/mwdb-core/blob/d593f697ebf37e036e778641038d5613ed852a5f/mwdb/cli/database.py#L57

But this is more complex than we need for our needs.