FROMLIST: gunyah: vm_mgr: Add framework for VM Functions

Introduce a framework for Gunyah userspace to install VM functions. VM
functions are optional interfaces to the virtual machine. vCPUs,
ioeventfs, and irqfds are examples of such VM functions and are
implemented in subsequent patches.

A generic framework is implemented instead of individual ioctls to
create vCPUs, irqfds, etc., in order to simplify the VM manager core
implementation and allow dynamic loading of VM function modules.

Bug: 338347082
Link: https://lore.kernel.org/all/20240222-gunyah-v17-13-1e9da6763d38@quicinc.com/


Change-Id: I57bca320b41ac0d9a7ee57bd9189c648de315d24
Signed-off-by: Elliot Berman <quic_eberman@quicinc.com>