rpc: gettxoutsetinfo can specify hash_type (only legacy option for now)

Summary:
This is a backport of core#19328 [2/4]
https://github.com/bitcoin/bitcoin/pull/19328/commits/a712cf6f6801157667fcf36d1c498b6fff6d328a

Backport note: D507 kept the name hash_serialized instead of using hash_serialized_2 which was introduced in core#10426

Depends on D9978

Test Plan: ninja all check-all

Reviewers: #bitcoin_abc, majcosta

Reviewed By: #bitcoin_abc, majcosta

Subscribers: majcosta

Differential Revision: https://reviews.bitcoinabc.org/D9979