[IMP] mail, *: move up model files

Move model definition files from `models/thing/thing.js` to
`models/thing.js` and remove the now empty intermediate directory.

Task-2759582
 * = calendar, crm_livechat, hr, im_livechat, mail_bot, sms, snailmail,
     website_livechat, website_slides

closes odoo/odoo#86464

Related: odoo/enterprise#25291
Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/sms/static/src/models/message.js

@@ -2,7 +2,7 @@
 
 import { patchRecordMethods } from '@mail/model/model_core';
 // ensure that the model definition is loaded before the patch
-import '@mail/models/message/message';
+import '@mail/models/message';
 
 patchRecordMethods('Message', {
     /**

addons/sms/static/src/models/notification_group.js

@@ -2,7 +2,7 @@
 
 import { patchRecordMethods } from '@mail/model/model_core';
 // ensure that the model definition is loaded before the patch
-import '@mail/models/notification_group/notification_group';
+import '@mail/models/notification_group';
 
 patchRecordMethods('NotificationGroup', {
     /**