[Feature] Frontend Testing #140 (#218)

I added playwright for frontend testing and got a couple simple test cases working.
I have updated pyproject.toml but it can also be installed with `pip install pytest-playwright` followed by `playwright install`

With the django server running you can do `playwright codegen http://localhost:8000/` which will generate test code based on the actions you take on the webpage it opens. Be sure to change the target to pytest in the code pop up.

I will add more test cases but @jebus and @t03i feel free to add more. Especially once we are done with the full front-end redesign.

I have put the tests under `tests/frontend/` but I am not sure how to add them to the CI. They give steps for CI integration but maybe we want to somehow include them in our exisiting CI yaml? https://playwright.dev/python/docs/ci-intro

Reviewed-on: enviPath/enviPy#218
Reviewed-by: Tobias O <tobias.olenyi@envipath.com>
Co-authored-by: Liam Brydon <lbry121@aucklanduni.ac.nz>
Co-committed-by: Liam Brydon <lbry121@aucklanduni.ac.nz>

.gitignore

@@ -6,6 +6,7 @@ static/django_extensions/
 .env
 debug.log
 scratches/
+test-results/
 
 data/