Create a management command to set up a sane pytest configuration

I propose we add a management command, maybe something like python manage.py setup_pytest which will create a sane pytest.ini with some default settings. I intend the generated file to look something like this.

The file itself will be generated using the iniconfig package which pytest already depends on. Looks like iniconfig is not capable of writing files, in which case, I will just generate the file using inbuilt strings.

Finally, relevant documentation will also need to be written.

I would make a PR to do all this, when (and if) this is accepted.

Start by reviewing Django's custom management command guidance and the proposed setup_pytest entry point. Compare the linked pytest.ini example with the defaults the command should generate, then determine where relevant documentation belongs. Done means the command creates a usable pytest.ini and the behavior is documented.