init: Refactor service.h/cpp

Factors out utility functions into service_utils.h/cpp, so that they
can be reused by the upcoming native zygote.

Bug: 133443795
Test: Build and boot cuttlefish.
Change-Id: I0531b6f17561119c8cc33dd9ba375b351747fcfe
diff --git a/init/Android.bp b/init/Android.bp
index 232d7e3..eaa7fd7 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -127,6 +127,7 @@
         "selabel.cpp",
         "selinux.cpp",
         "service.cpp",
+        "service_utils.cpp",
         "sigchld_handler.cpp",
         "subcontext.cpp",
         "subcontext.proto",
@@ -259,6 +260,7 @@
         "rlimit_parser.cpp",
         "tokenizer.cpp",
         "service.cpp",
+        "service_utils.cpp",
         "subcontext.cpp",
         "subcontext.proto",
         "util.cpp",