Implement management command for downloading location data

[SanketDG]

Description

After #572 gets merged, the repository will become larger by 60MB, which is not effecient.

So for downloading the GeoIP location data, one can use a manage command like:

python manage.py locationdata

This can also be integrated in the dev setup docs for beginners, and be used in the CI so that all checks are passed.

Tasks

• Implement the management command
• Make sure the command works on every platform
• Write insructions in the installation and the setup docs
• Integrate in the CI and make sure tests are passing
• Remove the old files (especially the MMDB files)

I'd be interested in mentoring someone formally for this PR. Please ping me on Zulip if you are relatively new here and you want to get started with your first PR!

[sakshi1499]

@anitab-org/coding-team Anybody who wants to work on it?