uefi-raw: add as_ptr() and as_mut_ptr() for IpAddress

In a nutshell, IpAddress is a buffer for Ipv4 or Ipv6
addresses. As UEFI functions consume pointers, having
this helper is very convenient, especially in
`uefi/src/proto/network/pxe.rs`.

The IpAddress type we want to replace in `uefi` with
the more mature base version from `uefi-raw` also has
corresponding helpers.

This also aligns with other data structures that act
as a buffer.

Author: phip1611

uefi-raw/CHANGELOG.md

@@ -18,6 +18,7 @@
   - `[u8; 16]` --> `Ipv6Address`, `IpAddress`
 - Added `::into_core_ip_addr()` for `IpAddress`
 - Added `::try_into_ethernet_mac_addr()` for `MacAddress`
+- Added `::as_ptr()` and  `::as_mut_ptr()` for `IpAddress`
 
 ## Changed
 - **Breaking:** The MSRV is now 1.85.1 and the crate uses the Rust 2024 edition.

uefi-raw/src/net.rs

@@ -165,6 +165,16 @@ impl IpAddress {
             core::net::IpAddr::V4(core::net::Ipv4Addr::from(unsafe { self.v4.octets() }))
         }
     }
+
+    /// Returns a const pointer to the underlying buffer.
+    pub fn as_ptr(&self) -> *const Self {
+        &raw const *self
+    }
+
+    /// Returns a mutable pointer to the underlying buffer.
+    pub fn as_mut_ptr(&self) -> *const Self {
+        &raw const *self
+    }
 }
 
 impl Debug for IpAddress {