Don't move scheduled drafts into subfolder if already there

Thunderbird was changed in release 115.2 so that if you edit a draft
that's in a subfolder of your Drafts folder and then save it, it goes
back into the same folder; previously it was saved into the default
Drafts folder for the account, not the subfolder. This broke Send
Later's "Store scheduled messages in subfolder" feature: if you edited
a scheduled message in a subfolder and then scheduled the edited
message, it would be saved in a subfolder of the subfolder instead of
saving in the subfolder it started in. This is now fixed.

utils/tools.js

@@ -221,6 +221,11 @@ var SLTools = {
     let subfolderName = preferences.subfolderName;
     if (!subfolderName) return;
     let folder = msg.folder;
+    // If the message is already in an appropriately named subfolder then
+    // don't go another level deep. Necessary starting in TB 115.2, because
+    // they changed TB so drafts loaded from a particular subfolder get saved
+    // back to that subfolder.
+    if (folder.path.endsWith("/" + subfolderName)) return;
     let found;
     let subfolder;
     for (subfolder of await messenger.folders.getSubFolders(folder)) {