FEATURE: Add scopes to API keys (#9844)

* Added scopes UI

* Create scopes when creating a new API key

* Show scopes on the API key show route

* Apply scopes on API requests

* Extend scopes from plugins

* Add missing scopes. A mapping can be associated with multiple controller actions

* Only send scopes if the use global key option is disabled. Use the discourse plugin registry to add new scopes

* Add not null validations and index for api_key_id

* Annotate model

* DEV: Move default mappings to ApiKeyScope

* Remove unused attribute and improve UI for existing keys

* Support multiple parameters separated by a comma

db/migrate/20200520124359_add_api_key_scopes.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+class AddApiKeyScopes < ActiveRecord::Migration[6.0]
+  def change
+    create_table :api_key_scopes do |t|
+      t.integer :api_key_id, null: false
+      t.string :resource, null: false
+      t.string :action, null: false
+      t.json :allowed_parameters
+      t.timestamps
+    end
+
+    add_index :api_key_scopes, :api_key_id
+  end
+end