Add test suite for Dashboard

[jescalada]

Add basic E2E tests for dashboard page:

• Ensure anything clickable leads to the right page with the right content
  • Links to Metrics page should show the right content
  • Links to experiments should show the Experiment page with relevant experiments
• Ensure test data displays correctly on dashboard
  • Number of runs, number of metrics displayed match the DB seeding script
• Ensure critical elements are displayed: Experiment selector, etc.
  • Experiment selector should be interactable and show a list of two default experiments (if using the k6 load script)
  • Contributions section leads to Runs page on appropriate date when clicked