DEV: configurable custom sidebar sections (#20057)

Allows users to configure their own custom sidebar sections with links withing Discourse instance. Links can be passed as relative path, for example "/tags" or full URL.

Only path is saved in DB, so when Discourse domain is changed, links will be still valid.

Feature is hidden behind SiteSetting.enable_custom_sidebar_sections. This hidden setting determines the group which members have access to this new feature.

db/migrate/20230115233416_create_sidebar_sections.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class CreateSidebarSections < ActiveRecord::Migration[7.0]
+  def change
+    create_table :sidebar_sections do |t|
+      t.integer :user_id, null: false
+      t.string :title, null: false
+      t.timestamps
+    end
+
+    add_index :sidebar_sections, %i[user_id title], unique: true
+  end
+end

db/migrate/20230117002110_create_sidebar_url.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class CreateSidebarUrl < ActiveRecord::Migration[7.0]
+  def change
+    create_table :sidebar_urls do |t|
+      t.string :name, null: false
+      t.string :value, null: false
+      t.timestamps
+    end
+  end
+end

db/migrate/20230118042740_add_sidebar_section_id_to_sidebar_section_links.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+class AddSidebarSectionIdToSidebarSectionLinks < ActiveRecord::Migration[7.0]
+  def change
+    add_column :sidebar_section_links, :sidebar_section_id, :integer, index: true
+  end
+end