[rpc_binder] Implement RPC binder over init-managed Unix domain socket

This implements an RPC binder over init-managed Unix domain sockets.
The cl adds binder tests and the new API is also used for
vm_payload_service inside Microdroid.
A previous cl aosp/2229557 sets up the binder over anonymous Unix sockets.

Test: atest MicrodroidTests ComposHostTestCases
Bug: 222479468
Change-Id: I0c7c38f4792c4536f5f88eb7e035091505f782f7
diff --git a/libs/binder/Android.bp b/libs/binder/Android.bp
index 2362580..28369d6 100644
--- a/libs/binder/Android.bp
+++ b/libs/binder/Android.bp
@@ -501,6 +501,7 @@
         "libbase",
         "libbinder",
         "libbinder_ndk",
+        "libcutils_sockets",
         "liblog",
         "libutils",
     ],