Merge remote-tracking branch 'remotes/ericb/tags/pull-bitmaps-2020-08-21' into staging

bitmaps patches for 2020-08-21

- Andrey Shinkevich: Enhance qcow2.py for iotest inspection of qcow2 images
- Max Reitz: Add block-bitmap-mapping migration parameter

# gpg: Signature made Fri 21 Aug 2020 15:05:07 BST
# gpg:                using RSA key 71C2CC22B1C4602927D2F3AAA7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>" [full]
# gpg:                 aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>" [full]
# gpg:                 aka "[jpeg image of size 6874]" [full]
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2  F3AA A7A1 6B4A 2527 436A

* remotes/ericb/tags/pull-bitmaps-2020-08-21:
  iotests: Test node/bitmap aliases during migration
  iotests.py: Let wait_migration() return on failure
  migration: Add block-bitmap-mapping parameter
  iotests: dump QCOW2 header in JSON in #303
  qcow2_format.py: support dumping metadata in JSON format
  qcow2_format.py: collect fields to dump in JSON format
  qcow2.py: Introduce '-j' key to dump in JSON format
  qcow2_format.py: Dump bitmap table serialized entries
  qcow2_format.py: pass cluster size to substructures
  qcow2_format.py: Dump bitmap directory information
  qcow2_format.py: dump bitmap flags in human readable way.
  qcow2_format.py: change Qcow2BitmapExt initialization method
  qcow2_format.py: make printable data an extension class member
  iotests: add test for QCOW2 header dump

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>