ANDROID: KVM: arm64: Add memory accounting for the VM pagetable memory

The current accounting for the VM stage-2 pagetable memory allows
tracking the memory for all the VMs in the system.
Improve the memory accounting of a VM by making it more granular and by
adding support for tracking the guest pagetable size for a specified VM.

Bug: 260238318
Bug: 278749606
Change-Id: I9d275ce09be077abe27388acb90062412446348d
Signed-off-by: Sebastian Ene <sebastianene@google.com>