cleanup: Prefer template strings

Template strings are much nicer than string concatenation, so use
them where possible; this excludes translatable strings and any
strings containing '/' (until we can depend on gettext >= 0.20[0]).

[0] https://savannah.gnu.org/bugs/?50920

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/612

js/ui/runDialog.js

@@ -199,7 +199,7 @@ class RunDialog extends ModalDialog.ModalDialog {
                 if (inTerminal) {
                     let exec = this._terminalSettings.get_string(EXEC_KEY);
                     let execArg = this._terminalSettings.get_string(EXEC_ARG_KEY);
-                    command = exec + ' ' + execArg + ' ' + input;
+                    command = `${exec} ${execArg} ${input}`;
                 }
                 Util.trySpawnCommandLine(command);
             } catch (e) {