[Chronik] Add Script::put_pushdata and Script::put_slp_pushdata

Summary: This is helpful when building SLP/ALP OP_RETURN scripts.

Test Plan: cargo test -p bitcoinsuite-core

Reviewers: Fabien, #bitcoin_abc, PiRK

Reviewed By: #bitcoin_abc, PiRK

Differential Revision: https://reviews.bitcoinabc.org/D15009