DEV: Database backed admin notices (#26192)

This PR introduces a basic AdminNotice model to store these notices. Admin notices are categorized by their source/type (currently only notices from problem check.) They also have a priority.

db/migrate/20240311015942_create_admin_notices.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+class CreateAdminNotices < ActiveRecord::Migration[7.0]
+  def change
+    create_table :admin_notices do |t|
+      t.integer :subject, null: false, index: true
+      t.integer :priority, null: false
+
+      t.string :identifier, null: false, index: true
+      t.json :details, null: false, default: {}
+
+      t.timestamps
+    end
+  end
+end

db/migrate/20240401054228_add_details_to_problem_check_trackers.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddDetailsToProblemCheckTrackers < ActiveRecord::Migration[7.0]
+  def change
+    add_column :problem_check_trackers, :details, :json, default: {}
+  end
+end

db/migrate/20240517014119_add_target_to_problem_check_trackers.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddTargetToProblemCheckTrackers < ActiveRecord::Migration[7.0]
+  def change
+    add_column :problem_check_trackers, :target, :string, null: true
+  end
+end

db/migrate/20240517051933_disambiguate_problem_check_tracker_uniqueness.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+class DisambiguateProblemCheckTrackerUniqueness < ActiveRecord::Migration[7.0]
+  def change
+    remove_index :problem_check_trackers, name: "index_problem_check_trackers_on_identifier"
+    add_index :problem_check_trackers, %i[identifier target], unique: true
+  end
+end