libprocessgroup: Move CgroupSetupCgroups() to libprocessgroup_setup

Only init uses SetupCgroups. This functionality is
moved from libprocessgroup to its own library, and only
init links to it.

Also, merge CgroupSetupCgroups() with CgroupMap::SetupCgroups()
because the former is just an alias of the latter, and
CgroupMap does not belong to libcgrouprc_setup.

Test: boots
Bug: 123664216
Change-Id: I941dc0c415e2b22ae663d43e30dc7a464687325e
Merged-In: I941dc0c415e2b22ae663d43e30dc7a464687325e
diff --git a/init/Android.bp b/init/Android.bp
index 8292aa0..e834e99 100644
--- a/init/Android.bp
+++ b/init/Android.bp
@@ -82,6 +82,7 @@
         "liblogwrap",
         "liblp",
         "libprocessgroup",
+        "libprocessgroup_setup",
         "libselinux",
         "libutils",
     ],