Allow sending text after `shrug`

¯\_(ツ)_/¯ IDK, I like to write something after, sometimes

Allow sending:

¯\_(ツ)_/¯ some text

By entering:

/shrug some text

It's supported in Element. If you did it in nheko, you just used to lose the
extra text.

Not putting text is still supported, a ternary operator makes sure a
space is only inserted if the text isn't empty, to avoid having a trailing
space.

src/TextInputWidget.cpp

@@ -703,7 +703,7 @@ TextInputWidget::command(QString command, QString args)
         } else if (command == "roomnick") {
                 emit changeRoomNick(args);
         } else if (command == "shrug") {
-                emit sendTextMessage("¯\\_(ツ)_/¯");
+                emit sendTextMessage("¯\\_(ツ)_/¯" + (args.isEmpty() ? "" : " " + args));
         } else if (command == "fliptable") {
                 emit sendTextMessage("(╯°□°)╯︵ ┻━┻");
         } else if (command == "unfliptable") {