terminal-util: move lock_dev_console() here

It doesn't really make sense to have that in dev-setup.c, which is
mostly about setting up /dev/, creating device nodes and stuff.

let's move it to the other stuff that deals with /dev/console's
peculiarities.

src/core/exec-invoke.c

@@ -32,7 +32,6 @@
 #include "chown-recursive.h"
 #include "copy.h"
 #include "data-fd-util.h"
-#include "dev-setup.h"
 #include "env-util.h"
 #include "escape.h"
 #include "exec-credential.h"