drafts: getSelection to differentiate clicks from drags.

We can use getSelection to distinguish between clicks and drags while
accessing the body of a saved draft.  Previously, the draft would be
restored when trying to select draft text to copy/paste.

Fixes #14447.

static/js/drafts.js

@@ -334,6 +334,10 @@ exports.launch = function () {
 
     function setup_event_handlers() {
         $(".restore-draft").on("click", function (e) {
+            if (document.getSelection().type === "Range") {
+                return;
+            }
+
             e.stopPropagation();
 
             const draft_row = $(this).closest(".draft-row");