[FIX] pad: FIX error on pad when switching projects.

Currently, when we have pad issue when we switch the pad to html
editor.
for Ex: In the Project app with the Collaborative Pad activated, if we
create a task and change the Project name multiple times (one having
the Collaborative Pad activated while the other not activated), then
at one point the Collaborative Pad doesn't show up and it will display
object object.
issue is due to object value of the url and it was not going to check for
the startwith 'http'.

So in this commit, When value is json method convert it to the json object
so the value must check proper condition for the startsWith(this.value, 'http').

closes odoo/odoo#63047

Taskid: 2336325
X-original-commit: 73bfe794351b2881fed041983b90f3d90025d23e
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>

addons/pad/static/src/js/pad.js

@@ -39,6 +39,9 @@ var FieldPad = AbstractField.extend({
             this.$(".oe_configured").addClass('d-none');
             return Promise.resolve();
         }
+        if (this.mode === 'edit' && typeof(this.value) === 'object') {
+            this.value = this.value.toJSON();
+        }
         if (this.mode === 'edit' && _.str.startsWith(this.value, 'http')) {
             this.url = this.value;
             // please close your eyes and look elsewhere...