cronet: jarjar androidx inside cronet

To make sure cronet's androidx does not conflict with anything.

Test: atest CronetApiTest
Change-Id: Iad05e489a82a27c2cb7be1e115359efec6bef907
diff --git a/Cronet/Android.bp b/Cronet/Android.bp
index 2e7e7cf..3ce88ef 100644
--- a/Cronet/Android.bp
+++ b/Cronet/Android.bp
@@ -97,6 +97,7 @@
         "cronet_impl_platform_java",
     ],
     apex_available: ["com.android.tethering"],
+    jarjar_rules: "jarjar-rules.txt",
     unsafe_ignore_missing_latest_api: true,
     dist_group: "android",
     // cronet is used as a shared library.