Convert Qt to new serialization
Summary:
This is a backport of Core PR19032 [1/4]
https://github.com/bitcoin/bitcoin/pull/19032/commits/65c589e45e8b8914698a0fd25cd5aafdda30869c
Test Plan:
ninja all check-all cmake .. -GNinja -DENABLE_BIP70=OFF ninja all check-all
Reviewers: #bitcoin_abc, Fabien
Reviewed By: #bitcoin_abc, Fabien
Subscribers: Fabien
Differential Revision: https://reviews.bitcoinabc.org/D9244