Automate placing on demand parachain orders for tests

[antonva]

In order to speed up local testing for on demand parachains on zombienet:

• [x] create a small subxt based tool that can connect to an arbitrary node
• [x] place a single on demand order
• [ ] place a batch of orders
• [ ] handle/expose pallet errors
• [ ] expose place_order call parameters to the cli

Link to code repo: !TODO

[eskimor]

What is the status on this actually?