[GSK-2497] Allow to connect multiple external mlworkers (#1740)

[Hartorn]

Main branch for multiple ml workers (not yet to be merged)

Description

Related Issue

Type of Change

• [ ] 📚 Examples / docs / tutorials / dependencies update
• [ ] 🔧 Bug fix (non-breaking change which fixes an issue)
• [ ] 🥂 Improvement (non-breaking change which improves an existing feature)
• [ ] 🚀 New feature (non-breaking change which adds functionality)
• [ ] 💥 Breaking change (fix or feature that would cause existing functionality to change)
• [ ] 🔐 Security fix

Checklist

• [ ] I've read the CODE_OF_CONDUCT.md document.
• [ ] I've read the CONTRIBUTING.md guide.
• [ ] I've updated the code style using make codestyle.
• [ ] I've written tests for all new methods and classes that I created.
• [ ] I've written the docstring in Google format for all the methods and classes that I used.