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

@@ -34,7 +34,7 @@ class core_component_testcase extends advanced_testcase {
     // To be changed if number of subsystems increases/decreases,
     // 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 = 67;
+    const SUBSYSTEMCOUNT = 65;
 
     public function setUp() {
         $psr0namespaces = new ReflectionProperty('core_component', 'psr0namespaces');