Add archived to dashboard and change homepage to only show active (ie not archived) courses

app/dashboards/course_dashboard.rb

@@ -15,6 +15,7 @@ class CourseDashboard < Administrate::BaseDashboard
     panopto_folders: Field::String.with_options(searchable: false),
     semester_start_date: Field::Date,
     title: Field::String,
+    archived: Field::Boolean,
     homepage: Field::String,
     toggl_project: Field::Number,
     unit_code: Field::String,
@@ -30,6 +31,7 @@ class CourseDashboard < Administrate::BaseDashboard
   COLLECTION_ATTRIBUTES = %i[
     title
     unit_code
+    archived
     homepage
     lectures
     work_items
@@ -42,6 +44,7 @@ class CourseDashboard < Administrate::BaseDashboard
     id
     title
     unit_code
+    archived
     homepage
     panopto_folders
     semester_start_date
@@ -59,6 +62,7 @@ class CourseDashboard < Administrate::BaseDashboard
   FORM_ATTRIBUTES = %i[
     title
     unit_code
+    archived
     homepage
     panopto_folders
     semester_start_date
@@ -75,7 +79,10 @@ class CourseDashboard < Administrate::BaseDashboard
   #   COLLECTION_FILTERS = {
   #     open: ->(resources) { resources.where(open: true) }
   #   }.freeze
-  COLLECTION_FILTERS = {}.freeze
+  COLLECTION_FILTERS = {
+    archived: ->(resources) { resources.where(archived: true) },
+    active: ->(resources) { resources.where(archived: false) }
+  }.freeze
 
   # Overwrite this method to customize how courses are displayed
   # across all pages of the admin dashboard.