tests(e2e): Test new repo dialog and behaviour

- screenshots and basic accessibility scan of collapsed and expanded sections
  - the dropdowns do not pass the accessibility checks, but I haven't found an easy fix
  - I manually confirmed the dropdown behaviour via orca and firefox, though

(cherry picked from commit 8d829a97b2)

tests/e2e/shared/forms.ts

@@ -7,6 +7,9 @@ export async function validate_form({page}: {page: Page}, scope: 'form' | 'field
     'span[data-tooltip-content',
     // exclude weird non-semantic HTML disabled content
     '.disabled',
+    // legacy dropdowns don't use semantic HTML yet,
+    // avoid using these where possible
+    '.ui.dropdown',
   ];
   await accessibilityCheck({page}, [scope], excludedElements, []);