feat(launcher): add configurable terminal command

The terminal command for launching applications was previously hardcoded to 'kitty', causing issues for users without it installed.

This change introduces a new setting, 'appLauncher.terminalCommand', allowing users to specify their preferred terminal emulator. The default value is set to 'xterm -e'.

The implementation includes:
- Defining the setting in 'Commons/Settings.qml'.
- Adding a text input in the launcher settings tab.
- Updating the application plugin to use the new setting.

Modules/Launcher/Plugins/ApplicationsPlugin.qml

@@ -142,7 +142,8 @@ Item {
           if (app.runInTerminal) {
             // If app.execute() fails for terminal apps, we handle it manually.
             Logger.log("ApplicationsPlugin", "Executing terminal app manually: " + app.name)
-            const command = ["kitty", "-e"].concat(app.command)
+            const terminal = Settings.data.appLauncher.terminalCommand.split(" ")
+            const command = terminal.concat(app.command)
             Quickshell.execDetached(command)
           } else if (app.execute) {
             // Default execution for GUI apps

Modules/Settings/Tabs/LauncherTab.qml

@@ -99,6 +99,16 @@ ColumnLayout {
     onToggled: checked => Settings.data.appLauncher.useApp2Unit = checked
   }
 
+  NTextInput {
+    label: I18n.tr("settings.launcher.settings.terminal-command.label")
+    description: I18n.tr("settings.launcher.settings.terminal-command.description")
+    Layout.fillWidth: true
+    text: Settings.data.appLauncher.terminalCommand
+    onEditingFinished: {
+      Settings.data.appLauncher.terminalCommand = text
+    }
+  }
+
   NDivider {
     Layout.fillWidth: true
     Layout.topMargin: Style.marginXL * scaling