[Feature Request] Create agent pools

**Is your feature request related to a problem? Please describe.**
I would like to be able to create agent pools using automation.

**Describe the solution you'd like**
`az pipelines pool create ...`

**Additional context**
We provision AKS clusters for development teams. These come with pre-provisioned service connections, containerised azure devops agents, etc. that can all be done using automation. But we cannot automatically create a new agent pool for them, it has to be done manually.