Moves the following units into libbitcoin_util or libbitcoin_common
since they are required by multiple libraries:
- bloom
- interfaces/handler
- merkleblock
- outputtype
https://github.com/bitcoin/bitcoin/pull/15638/commits/99517866b62c261f990e1f897502855afc12f2a7
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Depends on D5983
This is a partial backport of Core PR15638