`load_fake_data` management command improvements

[zarino]

TIL Django management commands have their own --verbosity flag!

But the main thing I’ve added is a way to automatically delete all teams and non-staff users (and any associated models, like memberships), before loading the fake data. This was useful when I needed to re-create teams to test out #55.

[codecov[bot]]

Codecov Report

Merging #59 (6fa10c2) into main (b31ffb9) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #59   +/-   ##
=======================================
  Coverage   76.55%   76.55%           
=======================================
  Files          35       35           
  Lines         951      951           
  Branches       52       52           
=======================================
  Hits          728      728           
  Misses        209      209           
  Partials       14       14