[WIP] Rewrite to Proxy class: (#5507)

* Rewrite to Proxy class:
- introduced new Friendica\Network\Proxy class for in exchange of proxy_*()
  functions
- moved also all PROXY_* constants there as Proxy::*
- removed now no longer needed mod/proxy.php loading as composer's auto-load
  will do this for us
- renamed those proxy_*() functions to better names:
  + proxy_init()           -> Proxy::init()         (public)
  + proxy_url()            -> Proxy::proxifyUrl()   (public)
  + proxy_parse_html()     -> Proxy::proxifyHtml()  (public)
  + proxy_is_local_image() -> Proxy::isLocalImage() (private)
  + proxy_parse_query()    -> Proxy::parseQuery()   (private)
  + proxy_img_cb()         -> Proxy::replaceUrl()   (private)

* Ops, need to set $a here ...

* CR request:
- moved Proxy class to Friendica\Module
- extended BaseModule

* Ops, no need for own instance of $a when self::getApp() is around.

* Proxy-rewrite:
- proxy_url() and proxy_parse_html() are both non-module functions (now
  methods)
- so they must be splitted into a seperate class
- also the SIZE_* and DEFAULT_TIME constants are both not relevant to module

* No instances from utility classes

* Fixed error:
- proxify*() is now located in `Friendica\Util\ProxyUtils`

* Moved back to original place, ops? How did they move here? Well, it was not
intended by me.

* Removed duplicate (left-over from split) constants and static array. Thank to
MrPetovan finding it.

* Renamed ProxyUtils -> Proxy and aliased it back to ProxyUtils.

src/Worker/CronJobs.php

@@ -9,13 +9,14 @@ use Friendica\BaseObject;
 use Friendica\Core\Cache;
 use Friendica\Core\Config;
 use Friendica\Database\DBA;
+use Friendica\Database\PostUpdate;
 use Friendica\Model\Contact;
 use Friendica\Model\GContact;
 use Friendica\Model\Photo;
 use Friendica\Model\User;
 use Friendica\Network\Probe;
 use Friendica\Protocol\PortableContact;
-use Friendica\Database\PostUpdate;
+use Friendica\Util\Proxy as ProxyUtils;
 
 require_once 'include/dba.php';
 require_once 'mod/nodeinfo.php';
@@ -159,9 +160,11 @@ class CronJobs
 			clear_cache($a->get_basepath(), $a->get_basepath() . "/proxy");
 
 			$cachetime = Config::get('system', 'proxy_cache_time');
+
 			if (!$cachetime) {
-				$cachetime = PROXY_DEFAULT_TIME;
+				$cachetime = ProxyUtils::DEFAULT_TIME;
 			}
+
 			$condition = ['`uid` = 0 AND `resource-id` LIKE "pic:%" AND `created` < NOW() - INTERVAL ? SECOND', $cachetime];
 			DBA::delete('photo', $condition);
 		}