drivers: hv: dxgkrnl: Open device object, adapter enumeration, dxgdev…

…ice, dxgcontext creation

- Handle opening of the device (/dev/dxg) file object and creation of
dxgprocess. dxgprocess is created for each process, which opens /dev/dxg.
dxgprocess is ref counted, so the exicting dxgprocess objects is used for
a process, which opens the device object multiple time.
dxgprocess is destroyed when the device object is closed.

- Implement ioctls for virtual GPU adapter enumeration:
LX_DXENUMADAPTERS2, LX_DXENUMADAPTERS3
The IOCTLs return a d3dkmt handle for each enumerated adapter.

- Implement ioctl to query adapter information:
LX_DXQUERYADAPTERINFO.

- Implement ioctls to open and closet a dxgadapter object:
LX_DXOPENADAPTERFROMLUID, LX_DXCLOSEADAPTER
Note that dxgadapter is opened when LX_DXENUMADAPTERS2, LX_DXENUMADAPTERS3
are called.

- Implement ioctls for dxgdevice and dxgcontext creation/destruction:
LX_DXCREATEDEVICE, LX_DXCREATECONTEXT, LX_DXCREATECONTEXTVIRTUAL,
LX_DXDESTROYCONTEXT, LX_DXCREATEHWCONTEXT, LX_DXDESTROYDEVICE,
LX_DXDESTROYHWCONTEXT

Signed-off-by: Iouri Tarassov <iourit@linux.microsoft.com>