Add machine pool logic

[dimakis]

Addition of some machine pool logic, which validates machine pool (replica) node count --but does not currently validate name, taint or labels constructs the payload and executes

Closes #

Verification Steps

1. Do x
2. Do y

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Documentation change
• [ ] Other (please specify)

[dimakis]

I've seen the demo of this working end to end. Thanks for the great work @dimakis

I'll let other experienced in the codebase have a look at the code.

Thanks a million for your great and thorough help on this. Always a pleasure working with you 😁