Add PackageManager.isSystemModule() for Spa

Bug: 236346018
Test: Manual with App Info page
Change-Id: If98fb841650c97b9a6648ce917d9bd016ba44d60

packages/SettingsLib/SpaPrivileged/src/com/android/settingslib/spaprivileged/model/app/PackageManagerExt.kt

@@ -0,0 +1,14 @@
+package com.android.settingslib.spaprivileged.model.app
+
+import android.content.pm.PackageManager
+
+/**
+ * Checks if a package is system module.
+ */
+fun PackageManager.isSystemModule(packageName: String): Boolean = try {
+    getModuleInfo(packageName, 0)
+    true
+} catch (_: PackageManager.NameNotFoundException) {
+    // Expected, not system module
+    false
+}