Create a guide for writing and running e2e tests

[cquinn540]

Terms

• I have searched open and closed feature requests
• I agree to follow activist's Code of Conduct

Description

We want to make the e2e tests accessible and usable for more than just the most active contributors. To do this it would help to have documentation on how to write e2e tests and what they should cover.

The e2e tests need to be improved before doing this so we have a good example for contributors to follow. This can be done after simplying the page objects #1047 and updating at least one test to use accessibility locators #1048.

Contribution

I also plan to work on this after the previous issues are resolved.