[FIX] mail: Message, MessageActionList in front of Composer

Prior this commit, the MessageActionList was behind and partly hidden by
the Composer when we edit small messages.

After this commit, the MessageActionList is in front of the Composer.

task-2819763

closes odoo/odoo#89610

Signed-off-by: Alexandre Kühn (aku) <aku@odoo.com>

addons/mail/static/src/components/message/message.scss

@@ -7,7 +7,8 @@
 // (eg. position-absolute top-0 end-0 mt-n3)
 .o_Message_actionListContainer {
     @include o-position-absolute($top: - map-get($spacers, 3), $right: 0);
-
+    z-index: 10; // Place the element in front of the Composer when they overlap
+    
     &.o-squashed {
         @include o-position-absolute($top: - map-get($spacers, 4), $right: 0);
     }