Create new virtmgr binary from virtualizationservice

To bootstrap separation of virtualizationservice into two binaries
(global service and user instance), start by compiling a second binary
out of the same source code, just using a diffrent main source file.

The new binary has a command line interface that takes two file
descriptors - a socketpair() fd to start RpcBinder server on, and
a pipe() fd to use for signalling when the server has been started.

The process registers a death notification to kill itself when the
parent process has died.

Bug: 245727626
Test: builds, not used in tests yet
Change-Id: I0c4c7892af91b6deb5ece60e0d1b49a2b4356d35
diff --git a/apex/Android.bp b/apex/Android.bp
index 579d7c7..d5f485b 100644
--- a/apex/Android.bp
+++ b/apex/Android.bp
@@ -73,6 +73,7 @@
         arm64: {
             binaries: [
                 "crosvm",
+                "virtmgr",
                 "virtualizationservice",
             ],
             filesystems: microdroid_filesystem_images,
@@ -80,6 +81,7 @@
         x86_64: {
             binaries: [
                 "crosvm",
+                "virtmgr",
                 "virtualizationservice",
             ],
             filesystems: microdroid_filesystem_images,