[Thread] Add support for Thread persistent setting

The ThreadPersistentSetting class can be used to read/store key value
pairs in ThreadPersistentSetting.xml file.

Bug: 299243765

Test: atest ThreadNetworkUnitTests:com.android.server.thread.ThreadPersistentSettingTest
Change-Id: I564ce8373e6af8f5cdf066a579bec46bfffecb72
diff --git a/thread/tests/unit/Android.bp b/thread/tests/unit/Android.bp
index 8092693..5116db5 100644
--- a/thread/tests/unit/Android.bp
+++ b/thread/tests/unit/Android.bp
@@ -40,6 +40,7 @@
         "mockito-target-minus-junit4",
         "net-tests-utils",
         "truth",
+        "service-thread-pre-jarjar",
     ],
     libs: [
         "android.test.base",