Slim down Docker image

Consider not installing as many dependencies via apt. I think we don't need to force everyone to have gcc installed for example if they don't use plugins.

For example:
https://github.com/CTFd/CTFd/pull/1782

I think this is best kept to a major release.

Start by reviewing the Docker image build and its apt dependency list, then compare the approach in PR 1782. Identify which packages are required by the base application versus optional plugins; done means the image no longer installs unnecessary dependencies while supported plugin use remains intact.

Written by the indexing model from the issue text.