[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.

mod/suggest.php

@@ -11,6 +11,7 @@ use Friendica\Core\System;
 use Friendica\Database\DBA;
 use Friendica\Model\Contact;
 use Friendica\Model\GContact;
+use Friendica\Util\Proxy as ProxyUtils;
 
 function suggest_init(App $a) {
 	if (! local_user()) {
@@ -51,11 +52,10 @@ function suggest_init(App $a) {
 
 }
 
-function suggest_content(App $a) {
-
-	require_once("mod/proxy.php");
-
+function suggest_content(App $a)
+{
 	$o = '';
+
 	if (! local_user()) {
 		notice(L10n::t('Permission denied.') . EOL);
 		return;
@@ -91,7 +91,7 @@ function suggest_content(App $a) {
 			'itemurl' => (($contact_details['addr'] != "") ? $contact_details['addr'] : $rr['url']),
 			'img_hover' => $rr['url'],
 			'name' => $contact_details['name'],
-			'thumb' => proxy_url($contact_details['thumb'], false, PROXY_SIZE_THUMB),
+			'thumb' => ProxyUtils::proxifyUrl($contact_details['thumb'], false, ProxyUtils::SIZE_THUMB),
 			'details'       => $contact_details['location'],
 			'tags'          => $contact_details['keywords'],
 			'about'         => $contact_details['about'],