Userland: Add support for jails

This happens in two ways:
1. LibCore now has two new methods for creating Jails and attaching
   processes to a Jail.
2. We introduce 3 new utilities - lsjails, jail-create and jails-attach,
   which list jails, create jails and attach processes to a Jail,
   respectively.

Base/usr/share/man/man1/lsjails.md

@@ -0,0 +1,22 @@
+## Name
+
+lsjails - list existing jails
+
+## Synopsis
+
+```**sh
+# lsjails
+```
+
+## Description
+
+This utility will list all existing jails at the moment of invoking this program.
+Please note that if the current process is in jail, it will not see any jail.
+
+## Examples
+
+```sh
+# lsjails
+Index   Name
+2       test-jail
+```