list sharing implemented w. passing UTs & FTs; changes to apps.dashboard.urls, .models, .views & .tests.test_views to accomodate; functional_tests.test_sharing also ensures sharing visible in UX; templates/apps/dashboard/list.html & /my_lists.html updated with django templating & for loops

src/apps/dashboard/urls.py

@@ -5,4 +5,5 @@ urlpatterns = [
     path('new_list', views.new_list, name='new_list'),
     path('<int:list_id>/', views.view_list, name='view_list'),
     path('users/<uuid:user_id>/', views.my_lists, name='my_lists'),
+    path('<int:list_id>/share_list', views.share_list, name="share_list"),
 ]