[kernel] Make capabilities/handles global

Instead of handles / capabilities having numeric ids that are only valid
for the owning process, they are now global in a system capabilities
table. This will allow for specifying capabilities in IPC that doesn't
need to be kernel-controlled.

Processes will still need to be granted access to given capabilities,
but that can become a simpler system call than the current method of
sending them through mailbox messages (and worse, having to translate
every one into a new capability like was the case before). In order to
track which handles a process has access to, a new node_set based on
node_map allows for an efficient storage and lookup of handles.

definitions/objects/process.def

@@ -26,6 +26,5 @@ object process : object {
     # object as the specified handle.
     method give_handle {
         param target ref object [handle]          # A handle in the caller process to send
-        param received ref object [out optional]  # The handle as the recipient will see it
     }
 }