Move utilities to libs/net

These files used to be in the network stack directory, but the libs
directory is a much more suitable place for them.

Also fix a typo : ConcurrentIntepreter → ConcurrentInterpreter

Also move {FdEvents,Packet}Reader to internal annotations. That's
what they should have been using in the first place anyway.

Note that this does not fix preupload issues reported by
checkstyle to make review easier. The fixes are in a followup
patch to this one.

Test: checkbuild
Change-Id: I675077fd42cbb092c0e6bd56571f2fc022e582fd
diff --git a/staticlibs/tests/unit/Android.bp b/staticlibs/tests/unit/Android.bp
index cb15277..f18ffcf 100644
--- a/staticlibs/tests/unit/Android.bp
+++ b/staticlibs/tests/unit/Android.bp
@@ -10,6 +10,8 @@
     static_libs: [
         "net-utils-framework-common",
         "androidx.test.rules",
+        "net-utils-device-common",
+        "net-tests-utils-host-device-common",
     ],
     libs: [
         "android.test.runner",