move canvg and rgbcolor libs to external

src/editor/extensions/ext-server_moinsave.js

@@ -7,7 +7,7 @@
  *  adopted for moinmoins item storage. It sends in one post png and svg data
  *  (I agree to dual license my work to additional GPLv2 or later)
  */
-import {canvg} from '../canvg/canvg.js';
+import {canvg} from '../../external/canvg/canvg.js';
 
 export default {
   name: 'server_moinsave',

src/editor/extensions/ext-server_opensave.js

@@ -6,7 +6,7 @@
  * @copyright 2010 Alexis Deveria
  *
  */
-import {canvg} from '../canvg/canvg.js';
+import {canvg} from '../../external/canvg/canvg.js';
 
 export default {
   name: 'server_opensave',