created functional_tests.list_page to handle common FT helpers; almost every FT file affected & less reliant on .base, which no longer contains those helpers

src/functional_tests/test_sharing.py

@@ -1,6 +1,8 @@
 from selenium import webdriver
 from selenium.webdriver.common.by import By
+
 from .base import FunctionalTest
+from .list_page import ListPage
 
 
 # Helper fns
@@ -25,10 +27,12 @@ class SharingTest(FunctionalTest):
 
         self.browser = disco_browser
         self.browser.get(self.live_server_url)
-        self.add_list_item("Send help")
+        list_page = ListPage(self).add_list_item("Send help")
 
-        share_box = self.browser.find_element(By.CSS_SELECTOR, 'input[name="shareable"]')
+        share_box = list_page.get_share_box()
         self.assertEqual(
             share_box.get_attribute("placeholder"),
             "friend@example.com",
         )
+
+        list_page.share_list_with("friend@example.com")