Implement support for some basic embed options for work sheets via LTI

This commit also fixes an issue with the flash messages being positioned too high and displayed for too long

app/controllers/application_controller.rb

@@ -5,7 +5,7 @@ class ApplicationController < ActionController::Base
   MEMBER_ACTIONS = [:destroy, :edit, :show, :update]
 
   after_action :verify_authorized, except: [:help, :welcome]
-  before_action :set_locale, :allow_iframe_requests
+  before_action :set_locale, :allow_iframe_requests, :load_embed_options
   protect_from_forgery(with: :exception, prepend: true)
   rescue_from Pundit::NotAuthorizedError, with: :render_not_authorized
 
@@ -38,4 +38,14 @@ class ApplicationController < ActionController::Base
   def allow_iframe_requests
     response.headers.delete('X-Frame-Options')
   end
+
+  def load_embed_options
+    if session[:embed_options].present? && session[:embed_options].is_a?(Hash)
+      @embed_options = session[:embed_options].symbolize_keys
+    else
+      @embed_options = {}
+    end
+    @embed_options
+  end
+  private :load_embed_options
 end