ANDROID: pkvm: introduce port I/O emulation framework

Add io_emulate.c and its header to place I/O emulation code for host vm.

Introduce a new data structure pkvm_pio_emul_table to store port I/O
handler. Add a helper function to register port I/O handler into the
emulation table. Define host_pio_emul_table for host port I/O emulation.

Signed-off-by: Tinghao Zhang <tinghao.zhang@intel.com>

Bug: 349990461
Test: Android can run protected VMs

Change-Id: I572d99fdc9ace5205e5269d7e177847926270d39
Signed-off-by: Dmytro Maluka <dmaluka@google.com>