blktap2: Redirect VBD pause events to sm/blktap.py
blktap2: Redirect VBD pause events to sm/blktap.py

Delegate blkback uevent handling to sm/blktap2.py, a drop-in
replacment for scripts/block.

Once blktap2 is enabled, the new module additionally manages
pause/resume for all tapdisk2 nodes. A VBD.pause/resume then will
pause/resume the tapdev node accordingly.

Signed-off-by: Daniel Stodden <05f14ed2a2851619d24030f51bb8d7a9bac70353@citrix.com>

djs55/xcp-rrdd,djs55/xcp-networkd,djs55/squeezed,koushikcgit/xcp-rrdd,simonjbeaumont/xcp-rrdd,koushikcgit/xcp-networkd,robhoes/squeezed,koushikcgit/xcp-rrdd,johnelse/xcp-rrdd,koushikcgit/xcp-rrdd,sharady/xcp-networkd,djs55/xcp-networkd,sharady/xcp-networkd,johnelse/xcp-rrdd,simonjbeaumont/xcp-rrdd,koushikcgit/xcp-networkd,djs55/xcp-rrdd