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
- [ ] Evaluate / Prioritize Feature Request
- [ ] Refine User Stories / Requirements
- [ ] Define Test Cases
- [ ] Design / Develop Solution
- [ ] Perform QA/Testing
- [ ] Update Documentation

No repository file, test, or entry point is named. Start by reviewing the build and deployment configuration for macOS and the linked GitHub Actions issue about adding Monterey; done means BitShares Core builds and its deployment workflow supports macOS 12.x.

Written by the indexing model from the issue text.