[IMP] website: add a shadow option on the header

Part of https://github.com/odoo/odoo/pull/38950


task-2087641

closes odoo/odoo#38950

Related: odoo/design-themes#183
Signed-off-by: Quentin Smetz (qsm) <qsm@odoo.com>

addons/website/views/snippets/snippets.xml

@@ -390,6 +390,10 @@
          groups="website.group_website_designer">
         <we-checkbox string="Show Sign In" data-customize-website-views="portal.portal_show_sign_in" data-reload="/"/>
         <we-colorpicker string="Background Color" data-customize-website-color="" data-color="menu"/>
+        <we-checkbox id="option_header_shadow" string="Shadow"
+                     data-customize-website-views="website.header_shadow"
+                     data-select-class="shadow"
+                     data-no-preview="true"/>
         <we-select string="Logo" data-reload="/">
             <we-button data-customize-website-views="website.website_name">Text</we-button>
             <we-button data-customize-website-views="website.layout_logo_show">Image</we-button>

addons/website/views/website_templates.xml

@@ -274,6 +274,12 @@
     </xpath>
 </template>
 
+<template id="header_shadow" inherit_id="website.layout" name="Header Shadow" active="False">
+    <xpath expr="//header" position="attributes">
+        <attribute name="t-attf-class" add="shadow" separator=" "/>
+    </xpath>
+</template>
+
 <template id="header_hoverable_dropdown" inherit_id="website.layout" name="Header Hoverable Dropdown" active="False">
     <xpath expr="//header" position="attributes">
         <attribute name="t-attf-class" add="o_hoverable_dropdown" separator=" "/>