macOS Monterey (12.x) support

User Story

macOS 12 Monterey was released on October 25, 2021.

As a user I'd like that we support it.

Note: keep an eye on the Github Actions issue which is about adding macOS Monterey: https://github.com/actions/virtual-environments/issues/3649 .

Impacts Describe which portion(s) of BitShares Core may be impacted by your request. Please tick at least one box.

[ ] API (the application programming interface)
[x] Build (the build process or something prior to compiled code)
[ ] CLI (the command line wallet)
[x] Deployment (the deployment process after building such as Docker, Travis, etc.)
[ ] DEX (the Decentralized EXchange, market engine, etc.)
[ ] P2P (the peer-to-peer network for transaction/block propagation)
[ ] Performance (system or user efficiency, etc.)
[ ] Protocol (the blockchain logic, consensus, validation, etc.)
[ ] Security (the security of system or user data, etc.)
[x] UX (the User Experience)
[ ] Other (please add below)

CORE TEAM TASK LIST