MDL-62138 core: remove core_register and core_publish

These components have no classes and no strings and have no purspose. Component core_hub is responsible
for storing data, defining classes and strings for site registration and course publishing

This also reverts MDL-61945

lib/tests/component_test.php

@@ -36,7 +36,7 @@ class core_component_testcase extends advanced_testcase {
      * this is defined here to annoy devs that try to add more without any thinking,
      * always verify that it does not collide with any existing add-on modules and subplugins!!!
      */
-    const SUBSYSTEMCOUNT = 68;
+    const SUBSYSTEMCOUNT = 66;
 
     public function setUp() {
         $psr0namespaces = new ReflectionProperty('core_component', 'psr0namespaces');