[Thread] Make ThreadConfiguraiton a system API

This CL adds 3 things as @SystemApi:
- The ThreadConfiguration class except the Builder nested class.
- The ThreadNetworkController#registerConfigurationCallback method.
- The ThreadNetworkController#unregisterConfigurationCallback method.

Bug: 342519412
Test: CtsThreadNetworkTestCases

Change-Id: I8d3e48b73d471af1515f251451a1259a4bde69af
diff --git a/thread/tests/cts/Android.bp b/thread/tests/cts/Android.bp
index c1cf0a0..6db7c9c 100644
--- a/thread/tests/cts/Android.bp
+++ b/thread/tests/cts/Android.bp
@@ -21,9 +21,11 @@
 
 android_test {
     name: "CtsThreadNetworkTestCases",
-    defaults: ["cts_defaults"],
+    defaults: [
+        "cts_defaults",
+        "framework-connectivity-test-defaults",
+    ],
     min_sdk_version: "33",
-    sdk_version: "test_current",
     manifest: "AndroidManifest.xml",
     test_config: "AndroidTest.xml",
     srcs: [