Search built in to the "user" type field is broken

[ChemiKyle]

Complete user search is broken, and must have been for some time for forms with fields of type user.

To recreate:

• Use REDCap 9.3.5 or greater (possibly earlier)
• Enable the protocols_advanced module
• Enable the module on any project
• Navigate to the "Protocols" page
• Attempt to select a PI
• Observe that the list never populates

The root of the issue is here:

redcap_entity/manager/js/entity_fields.js

Lines 57 to 65 in c8cfdff

	ajax: {
	url: app_path_webroot + 'UserRights/search_user.php',
	dataType: 'json',
	cache: true,
	delay: 250,
	data: function (params) {
	params.searchEmail = true;
	return params;
	},

At some point, the UserRights/search_user.php endpoint began requiring a term in the GET data and it cannot be set to empty string.

---

A good candidate to replace the call to this page may be the Project->getUsers() function, although this requires a Project object be available and is scoped to the project from which it is called.
Better would be to find a way to get an empty string or wildcard in to the term arg:

data: function (params) { 
         params.searchEmail = true; 
         params.term = wildcardChar;
         return params; 
     }, 

Also consider hijacking the user-listcall made by the ExternalModules config menu.