[FIX] website_form: have several date picker

When multiple date (or datetime) pickers are added to a website form,
the uniqueId value is used to differenciate them thanks to 694af9a19a.

It works well in a lot of case (eg. when adding several field at the
same time, or by change because other code consume uniqueId) but in this
scenario:

- add a date field on a form
- save
- add a date field on a form

it is possible have the second field targetting the first one because
they have the same `'datepicket'+uniqueId()` ID. This happens because
uniqueId is reset at each page opening.

found when working on opw-2326882
closes #57092

closes odoo/odoo#57110

X-original-commit: 75ad994a628ef0d994b44cf6e25fd5340c3ecafd
Signed-off-by: Nicolas Lempereur (nle) <nle@odoo.com>

addons/website_form/static/src/xml/website_form_editor.xml

@@ -171,7 +171,7 @@
     <!-- Date Field -->
     <t t-name="website_form.field_date">
         <t t-call="website_form.field">
-            <t t-set="datepickerID" t-value="_.uniqueId('datepicker')"/>
+            <t t-set="datepickerID" t-value="'datepicker' + Math.random().toString().substring(2)"/>
             <div class="s_website_form_date input-group date" t-att-id="datepickerID" data-target-input="nearest">
                 <input
                         type="text"
@@ -192,7 +192,7 @@
     <!-- Datetime Field -->
     <t t-name="website_form.field_datetime">
         <t t-call="website_form.field">
-            <t t-set="datetimepickerID" t-value="_.uniqueId('datetimepicker')"/>
+            <t t-set="datetimepickerID" t-value="'datetimepicker' + Math.random().toString().substring(2)"/>
             <div class="s_website_form_datetime input-group date" t-att-id="datetimepickerID" data-target-input="nearest">
                 <input
                         type="text"