android: read the activity's own arguments, since Qt does not deliver them

`am start -n <pkg>/org.qtproject.qt.android.bindings.QtActivity --esa
applicationArguments "--workspace,/sdcard/x"` left the window on its default
workspace on the NX789J (the plain-string extra too), so the extra is read
from the intent directly. That is what makes `cst-agent-app --uitest
--workspace DIR` reachable on a device with no keyboard -- and adb cannot
inject touch into this window either (tap, touchscreen tap, mouse tap and
motionevent all do nothing; key events do work), so it is the only way in.

Everything degrades to "no arguments": an invalid object, a missing method or
a context that is not an activity all come back empty.

app/src/platform/android/AndroidTools.cpp

@@ -101,6 +101,41 @@ QJniObject appContext() {
   return QNativeInterface::QAndroidApplication::context();
 }
 
+/* The strings the activity was started with. Qt is meant to hand the
+ * "applicationArguments" extra to QCoreApplication::arguments() by itself; on
+ * the NX789J it does not -- `am start ... --esa applicationArguments
+ * "--workspace,/sdcard/x"` left the window on its default workspace, and so
+ * did the same extra as a plain string. So the intent is asked directly, which
+ * is what makes `cst-agent-app --uitest --workspace DIR` (or any other
+ * argument) reachable on a device with no keyboard attached.
+ *
+ * Everything here degrades to "no arguments": an invalid object, a missing
+ * method, or a context that is not an activity all come back empty. */
+QStringList intentArguments() {
+  QStringList out;
+  QJniObject activity = appContext();
+  if (!activity.isValid())
+    return out;
+  QJniObject intent =
+      activity.callObjectMethod("getIntent", "()Landroid/content/Intent;");
+  if (!intent.isValid())
+    return out;
+  QJniObject list = intent.callObjectMethod(
+      "getStringArrayListExtra", "(Ljava/lang/String;)Ljava/util/ArrayList;",
+      QJniObject::fromString(QStringLiteral("applicationArguments"))
+          .object<jstring>());
+  if (!list.isValid())
+    return out;
+  const jint n = list.callMethod<jint>("size", "()I");
+  for (jint i = 0; i < n; i++) {
+    QJniObject item =
+        list.callObjectMethod("get", "(I)Ljava/lang/Object;", i);
+    if (item.isValid())
+      out << item.toString();
+  }
+  return out;
+}
+
 /* --- notification_send --------------------------------------------------- */
 
 /* Android 13 (API 33) put notifications behind a runtime permission; before
@@ -516,6 +551,11 @@ cst_tool_def_t g_share;
 
 }  // namespace
 
+/* What main() asks for (ToolProvider.h): the reading itself is the JNI helper
+ * above, next to the Android context it needs. It sits outside the anonymous
+ * namespace so main.cpp can link to it. */
+QStringList activityArguments() { return intentArguments(); }
+
 /* A file card's "open": whatever app the phone has for the type, with the read
  * permission granted to the app that picks it up. */
 QString openLocalFile(const QString &path, const QString &title,