QA: blocktools: Accept block template to create_block

Summary:
The goal here is to decouple unrelated tests from the details of block versions.
Currently, these tests are forcing specific versions of blocks for no real reason.

This is a backport of core#19401 [1/2]
https://github.com/bitcoin/bitcoin/pull/19401/commits/1df2cd1c8f468bd7a5b1335a46ccea28fbddaacb

Note that the txlist parameter from the original commit is not going to be useful in Bitcoin ABC (as of today in Bitcoin Core it is only used on feature_taproot.py)

Test Plan: ninja check-functional-extended

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10688