[refactor] Split the message macro in a standalone library for reuse

This simplifies the task of creating an independent library of
rkpd_client later.

Test: atest keystore2_test
Bug: 241428146
Change-Id: Idddf37d14580e691fde5a494e54297465cb693b6
diff --git a/keystore2/Android.bp b/keystore2/Android.bp
index dd036c2..03dfd45 100644
--- a/keystore2/Android.bp
+++ b/keystore2/Android.bp
@@ -55,6 +55,7 @@
         "liblibc",
         "liblog_event_list",
         "liblog_rust",
+        "libmessage_macro",
         "librand",
         "librustutils",
         "libserde",