[MS54.1] Move NetworkStats to updatable sources

This CL builds NetworkStats related code with the
connectivity module instead of platform.

This includes:
1. Add netstats.proto to the module.
2. Add lib dependencies for all callers.
3. Include several source files in platform and add jarjar rule
   to it. Modify callers accordingly.

Test: TH
Bug: 197717846
Change-Id: I244693aebe1782d9e67502638ff8145c51462e1e

Android.bp

@@ -583,6 +583,7 @@ stubs_defaults {
     libs: [
         "art.module.public.api",
         "sdk_module-lib_current_framework-tethering",
+        "sdk_module-lib_current_framework-connectivity-tiramisu",
         "sdk_public_current_framework-bluetooth",
         // There are a few classes from modules used by the core that
         // need to be resolved by metalava. We use a prebuilt stub of the