[vmbase] Move RangeExt to vmbase for reuse

in both pvmfw and rialto.

No behavior change in this cl.

Bug: 284462758
Test: m pvmfw_img
Change-Id: Ifda7f4a2a08ebb6646c3c7e189a77c5ff3fe74a3
diff --git a/pvmfw/src/virtio/hal.rs b/pvmfw/src/virtio/hal.rs
index ce246b1..c8b279d 100644
--- a/pvmfw/src/virtio/hal.rs
+++ b/pvmfw/src/virtio/hal.rs
@@ -15,7 +15,6 @@
 //! HAL for the virtio_drivers crate.
 
 use super::pci::PCI_INFO;
-use crate::helpers::RangeExt as _;
 use crate::memory::{alloc_shared, dealloc_shared};
 use core::alloc::Layout;
 use core::mem::size_of;
@@ -23,6 +22,7 @@
 use log::trace;
 use virtio_drivers::{BufferDirection, Hal, PhysAddr, PAGE_SIZE};
 use vmbase::memory::{phys_to_virt, virt_to_phys};
+use vmbase::util::RangeExt as _;
 
 /// The alignment to use for the temporary buffers allocated by `HalImpl::share`. There doesn't seem
 /// to be any particular alignment required by VirtIO for these, so 16 bytes should be enough to