Moved CONTACT_* constants to Friendica\Model\Contact class, lesser in global namespace (#5490)

* Rewrite:
- moved all CONTACT_* constants from boot.php to Contact class

* CR request:
- renamed Contact::CONTACT_IS_* -> Contact::* ;-)

src/Network/Probe.php

@@ -14,6 +14,7 @@ use Friendica\Core\Cache;
 use Friendica\Core\Config;
 use Friendica\Core\System;
 use Friendica\Database\DBA;
+use Friendica\Model\Contact;
 use Friendica\Model\Profile;
 use Friendica\Protocol\Email;
 use Friendica\Protocol\Feed;
@@ -447,7 +448,7 @@ class Probe
 						'pubkey' => $data['pubkey'],
 						'priority' => $data['priority'],
 						'writable' => true,
-						'rel' => CONTACT_IS_SHARING];
+						'rel' => Contact::SHARING];
 
 				$fieldnames = [];