[FIX] web_editor: ensure snippet selection is kept when acting in it

The snippet selection was lost on every action in mass mailing. The code
that prevents that was checking if the target of a click was the body
element but for mass mailing we needed to be a little bit more
restrictive since the editable area is not the body itself and we want
to actually prevent changing the snippet selection when the target is
the iframe target as well.
Since the mailing itself has a options, the sidebar is actually never
empty and therefore removing a snippet doesn't bring us back to the
block tab. Since therefore also ensures that we actually do.

task-2716397

X-original-commit: ecdb71bf6a566f5f6c294904e84f2132561dbb3c
Part-of: odoo/odoo#81662

addons/web_editor/static/src/js/editor/snippets.editor.js

@@ -460,9 +460,14 @@ var SnippetEditor = Widget.extend({
         // first, destroying the related editors and not calling onBlur... to
         // check if this has always been like this or not and this should be
         // unit tested.
-        const parent = this.$target[0].parentElement;
+        let parent = this.$target[0].parentElement;
         const nextSibling = this.$target[0].nextElementSibling;
         const previousSibling = this.$target[0].previousElementSibling;
+        if ($(parent).is('.o_editable:not(body)')) {
+            // If we target the editable, we want to reset the selection to the
+            // body. If the editable has options, we do not want to show them.
+            parent = $(parent).closest('body');
+        }
         this.trigger_up('activate_snippet', {
             $snippet: $(previousSibling || nextSibling || parent)
         });
@@ -1293,7 +1298,7 @@ var SnippetsMenu = Widget.extend({
             if (!$target.closest('we-button, we-toggler, we-select, .o_we_color_preview').length) {
                 this._closeWidgets();
             }
-            if (!$target.closest('body > *').length) {
+            if (!$target.closest('body > *').length || $target.is('#iframe_target')) {
                 return;
             }
             if ($target.closest(this._notActivableElementsSelector).length) {