Add bilingual message type

Summary:
This is a partial backport of Core PR16362 : https://github.com/bitcoin/bitcoin/pull/16362/commits/7c45e14f2f682eddcc853c0f6051c7c8c6387289

Depends on D6048

Test Plan:

ninja all check-all

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D6050