Remove Ptr, RawPtr, GuestPtr, Offset, AddressSpace, GuestAddressSpace

[ludfjig]

Certain drivers used RawPtr and others used u64. To unify these in preparation for a refactor, they are replaced them with u64 instead.

The removed types were mostly unused and provided minimal benefit over a simple u64. Instead they just introduced overhead of converting to and from the pointer types. In the future we should think about introducing some type to abstract over phys/virtual addresses etc, or provide new pointer types with some security benefit like bounds checking or something else useful.

[syntactically]

In preparation for making Hyperlight more portable, one small thing from a commit series near the beginning of my big guest-CoW branch incidentally adds the types hyperlight_common::vm::{Virt,Phys}Addr, which are aliased to architecture-specific definition that are (for x86_64 and arm64) presently aliased to u64. I don't know if we ever plan to support non-64-bit targets, and the fact that they are aliases rather than newtypes makes them extremely lightweight, so they are more for documentation than anything else---but I think it does help documentation to be clear in this way when something is expecting a virtual vs. physical address. Would it be interesting to use those types instead of raw u64 here?