[era] Move test_wiped_blocks_have_increasing_eras to it's own file, and improve
[era] EraStatus class
fluff
[era] Add EraStack#checkpoint

This sends the checkpoint message and retrieves the current era via
the status.
[era] test_many_eras_does_not_exhaust_metadata
[cache] lift cache_utils, cache_policy and cache_stack to dmtest so I can use in the era tests
[era] Lift era_stack, era_utils, era_status
[era] era tracking tests
update dm cache status parsing
update dm cache status parsing to handle policy_name

update test_status to verify that "default" policy is reported as "mq"
in the cache status -- brittle if we alter which policy is the "default"
but...
cant_provision_new_blocks must use error_if_no_space

otherwise the wipe_device to the thin device will hang
thin: add pool_without_thin_devices_does_not_commit
thin: add resize_io_metadata

it isn't working properly.. partially due to test bug (resize isn't
firing).. but kernel currently won't work anyway due to metadata
spacemap issues -- metadata commit is failing with -ENOSPC
thin: add additional operations at the end of 'resize_io' test

verify the issues Kabi reported are fixed