Added a new socket to Zygote init scripts.

This change adds new socket declarations to the init scripts for the
Zygote processes.  This socket is used for communication between the
System Server and the Blastula pool.

Bug: 68253328
Topic: zygote-prefork
Test: build image; flash device; launch apps
Change-Id: I5dbb87770b1a3100c6c122bb39ca854006bb0b0d
Merged-In: I5dbb87770b1a3100c6c122bb39ca854006bb0b0d