MB-9979 Some mb_map refactoring.

So that functions that match past maps could be used outside mb_map
module.

Change-Id: Ia7247981ffc5e201dd2eeba52da949b4179fac60
Reviewed-on: http://review.couchbase.org/34220
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-9979 Implement delta recovery.

Change-Id: I898d4fe2e656dfdebc479e4cb532fd71cf0020db
Reviewed-on: http://review.couchbase.org/34221
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
MB-9979 Store target map for delta recovery in bucket config.

So that it can be reused if rebalance fails or gets stopped by user.

Change-Id: I3a91575aa0858476075e2b26f017aee25e60f910
Reviewed-on: http://review.couchbase.org/34222
Tested-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>
Reviewed-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>