Add -avoidpartialspends and m_avoid_partial_spends

Summary: This is a partial backport of Core PR12257 : https://github.com/bitcoin/bitcoin/pull/12257/commits/bb629cb9dc567cc819724d9f4852652926e60cbf

Test Plan:

make check

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D3392