[CMAKE] Run test/util/bitcoin-util-test.py with ninja check
[CMAKE] Run test/util/bitcoin-util-test.py with ninja check

Summary:
Add a few new rules to cmake:
 - `bitcoin-util-test` will run bitcoin-util-test.py
 - `check` now includes `bitcoin-util-test`
This mimics the behaviour of `make check` with autotools

Test Plan:
  mkdir buildcmake && cd buildcmake
  cmake -GNinja ..
  ninja bitcoin-util-test
  ninja check

Should return an unknown target error, as bitcoin-tx is required:
  cmake -DBUILD_BITCOIN_TX=OFF -GNinja .. && ninja bitcoin-util-test

Should run the tests but not bitcoin-util-test:
  cmake -DBUILD_BITCOIN_TX=OFF -GNinja .. && ninja check

Reviewers: #bitcoin_abc, deadalnix

Reviewed By: #bitcoin_abc, deadalnix

Subscribers: teamcity, schancel

Differential Revision: https://reviews.bitcoinabc.org/D2494

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