[IMP] website: add ID on snippet option elements

Needed in design-themes to be able to add selector to those elements.

Part of https://github.com/odoo/odoo/pull/42937
task-2088157
task-2152191

addons/website/views/snippets/snippets.xml

@@ -139,7 +139,7 @@
     </div>
 
     <!-- H-ALIGN | .s_btn -->
-    <div data-selector=".s_btn, .s_share">
+    <div id="so_text_align" data-selector=".s_btn, .s_share">
         <we-select string="Alignment">
             <we-button data-select-class="text-left">Left</we-button>
             <we-button data-select-class="text-center">Center</we-button>
@@ -147,7 +147,7 @@
         </we-select>
     </div>
 
-    <div data-selector=".s_alert, .s_card">
+    <div id="so_width" data-selector=".s_alert, .s_card">
         <we-select string="Width">
             <we-button data-select-class="w-25">25%</we-button>
             <we-button data-select-class="w-50">50%</we-button>