haven: Add VM management support for clients

Add VM management APIs so that clients can start VMs and allocate/get
vmids associated with VMs.

Change-Id: I7a9138a9479665f6c09aae98390a30c23011b3b1
Signed-off-by: Prakruthi Deepak Heragu <pheragu@codeaurora.org>
Signed-off-by: Elliot Berman <eberman@codeaurora.org>