Base/CI: Boot serenity in CI in a mode that runs tests on target

Build a new version of Serenity in CI that doesn't have all the debug
symbols on, or we'd be waiting a very long time to boot.

Insert a TestRunner entry into SystemServer.ini that will run a shell
script that runs tests in /bin and /usr/Tests and shuts down the system
in the new self-test boot mode. Also make sure enough basic services are
started in self-test such that the tests will actually run properly.

Base/etc/SystemServer.ini

@@ -4,7 +4,7 @@ SocketPermissions=660
 Lazy=1
 Priority=low
 User=protocol
-BootModes=text,graphical
+BootModes=text,graphical,self-test
 MultiInstance=1
 AcceptSocketConnections=1
 
@@ -39,13 +39,13 @@ Lazy=1
 Priority=low
 KeepAlive=1
 User=lookup
-BootModes=text,graphical
+BootModes=text,graphical,self-test
 
 [DHCPClient]
 Priority=low
 KeepAlive=1
 User=root
-BootModes=text,graphical
+BootModes=text,graphical,self-test
 
 [NotificationServer]
 Socket=/tmp/portal/notify
@@ -175,3 +175,11 @@ AcceptSocketConnections=1
 Executable=/bin/CrashDaemon
 KeepAlive=1
 User=anon
+
+[TestRunner@ttyS0]
+Executable=/home/anon/tests/run-tests-and-shutdown.sh
+StdIO=/dev/ttyS0
+Environment=DO_SHUTDOWN_AFTER_TESTS=1 TERM=xterm PATH=/bin:/usr/bin:/usr/local/bin
+User=anon
+WorkingDirectory=/home/anon
+BootModes=self-test