Add end-to-end (system) tests (#25461)

Gemfile.lock

@@ -199,6 +199,10 @@ GEM
     crass (1.0.6)
     css_parser (1.14.0)
       addressable
+    database_cleaner-active_record (2.1.0)
+      activerecord (>= 5.a)
+      database_cleaner-core (~> 2.0.0)
+    database_cleaner-core (2.0.1)
     date (3.3.3)
     debug_inspector (1.1.0)
     devise (4.9.2)
@@ -656,6 +660,10 @@ GEM
     scenic (1.7.0)
       activerecord (>= 4.0.0)
       railties (>= 4.0.0)
+    selenium-webdriver (4.9.1)
+      rexml (~> 3.2, >= 3.2.5)
+      rubyzip (>= 1.2.2, < 3.0)
+      websocket (~> 1.0)
     semantic_range (3.0.0)
     sidekiq (6.5.9)
       connection_pool (>= 2.2.5, < 3)
@@ -768,6 +776,7 @@ GEM
       rack-proxy (>= 0.6.1)
       railties (>= 5.2)
       semantic_range (>= 2.3.0)
+    websocket (1.2.9)
     websocket-driver (0.7.5)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
@@ -804,6 +813,7 @@ DEPENDENCIES
   color_diff (~> 0.1)
   concurrent-ruby
   connection_pool
+  database_cleaner-active_record
   devise (~> 4.9)
   devise-two-factor (~> 4.1)
   devise_pam_authenticatable2 (~> 9.2)
@@ -885,6 +895,7 @@ DEPENDENCIES
   rubyzip (~> 2.3)
   sanitize (~> 6.0)
   scenic (~> 1.7)
+  selenium-webdriver
   sidekiq (~> 6.5)
   sidekiq-bulk (~> 0.2.0)
   sidekiq-scheduler (~> 5.0)