feat: Add an option to register allowed ranges of memory

Certain kernel helpers return pointers to kernel managed memory, which
the ebpf program is allowed to load and read.
In order to implement stubs for these using rbpf, we need a way to mark
these ranges of memory as safe for the check_mem function.

The API specifically deals with adresses, because helpers need to be
function types and not closures. This means the pointers to objects
returned from them need to be static, and dealing with references to
static objects gets clunky. So I have chosen to push the obtaining of
the addresses into calling code.