N°4515 Fix default validation pattern for AttributeURL (#249)

URL containing ":" in their path were rejected. This caused problems with some URL from Alfresco or Sharepoint...
The default regexp used by AttributeURL was updated to avoid this.
Warning, check your config to see if you have any custom regexp configured (`url_validation_pattern` config parameter) !

Also a test was added to document the default regexp.

test/core/AttributeDefTest.inc.php

@@ -29,5 +29,4 @@ class AttributeDefTest extends ItopDataTestCase {
 		$this->assertEquals(["status" => "ENUM('active','inactive') CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci"],
 			$aImportColumns);
 	}
-
 }