Enforce the use of TxId when constructing COutPoint

Summary:
OutPoint refer to previous transaction ids, and shouldn't accept any hash as input when constructed.

Depends on D3641, D3643, D3644, D3646 and D3645

Test Plan:

make check

Reviewers: #bitcoin_abc, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Subscribers: jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D3647