Add Playwright UI test framework to datagov-harvester

[btylerburton]

User Story

In order to ensure reliable end-to-end testing, datagovteam wants to incorporate an end-to-end testing framework, and Playwright is an alternative to Cypress so tests can be written in Python.

Acceptance Criteria

[ACs should be clearly demoable/verifiable whenever possible. Try specifying them using BDD.]

• GIVEN I have configured Playwright in the datagov-harvester
  WHEN I invoke the test runner
  THEN I expect to see results from valid E2E tests

Background

Playwright includes direct integration with pytest: https://playwright.dev/python/docs/intro#installing-playwright-pytest

Security Considerations (required)

[Any security concerns that might be implicated in the change. "None" is OK, just be explicit here!]

Sketch

• Integrate playwright with pytest
• Write some tests of UI library

[rshewitt]

/harvest_job/ route doesn't work. forgot i found this. I figure this ticket would include tests against all routes. maybe this isn't the right place to put it but i want to mention it.

[rshewitt]

appears there isn't a formal playwright python config file compared to ts/js but there's a feature ticket for it which encourages configuring via pytest.ini file. usage doc does the same thing. looks like pytest can be configured in pyproject.toml. pytest config options