Add force_login option to OAuth authorize page (#8655)

* Add force_login option to OAuth authorize page

For when a user needs to sign into an app from multiple accounts
on the same server

* When logging out from modal header, redirect back after re-login

app/controllers/api/base_controller.rb

@@ -53,10 +53,6 @@ class Api::BaseController < ApplicationController
     [params[:limit].to_i.abs, default_limit * 2].min
   end
 
-  def truthy_param?(key)
-    ActiveModel::Type::Boolean.new.cast(params[key])
-  end
-
   def current_resource_owner
     @current_user ||= User.find(doorkeeper_token.resource_owner_id) if doorkeeper_token
   end