7.1.x Fix for UrlMapping greedy not working when no id is present

[codeconsole]

Follow up to #15213

"/$controller/$action?/$id?(.$format)?"

resulted in /user.json not matching. only /user would match. This fixes that.

Is seems like the best pathway forward to support formats and string $id's with .'s is the following mapping:

  // First: greedy with format constraint                                                                                              
  "/$controller/$action/$id+(.$format)?" {                                                                                             
      constraints {                                                                                                                    
          format(inList: ['json', 'xml', 'html', 'csv'])                                                                               
      }                                                                                                                                
  }                                                                                                                                    
  // Second: fallback for IDs with dots but no valid format                                                                            
  "/$controller/$action/$id"()  

URL	id	format	Which mapping?
/user/show/bob.smith	bob.smith	null	Fallback (no valid format)
/user/show/bob.smith.json	bob.smith	json	Greedy (valid format)
/user/show/bob.smith.jones	bob.smith.jones	null	Fallback (no valid format)
/user/show/bob.smith.jones.xml	bob.smith.jones	xml	Greedy (valid format)