[project] Generate syscalls from new interface DSL

This change adds a new interface DSL for specifying objects (with
methods) and interfaces (that expose objects, and optionally have their
own methods).

Significant changes:

- Add the new scripts/definitions Python module to parse the DSL
- Add the new definitions directory containing DSL definition files
- Use cog to generate syscall-related code in kernel and libj6
- Unify ordering of pointer + length pairs in interfaces

src/kernel/vm_space.h

@@ -103,7 +103,7 @@ public:
     /// \arg to     Pointer to the destination in the dest address space
     /// \arg length Amount of data to copy, in bytes
     /// \returnd    The number of bytes copied
-    static size_t copy(vm_space &source, vm_space &dest, void *from, void *to, size_t length);
+    static size_t copy(vm_space &source, vm_space &dest, const void *from, void *to, size_t length);
 
 private:
     friend class vm_area;