Forking relaychain states with a testnet + executing XCM calls to forked instances

[flipchan]

Interesting post by Liam here:
polkadot-fellows/runtimes#83

[flipchan]

If someone else handles the forking and spinning up a testnet. Uptest cli tool could provide functionality to:

• 1: submit the wasm runtime upgrade
• 2: wait for the the runtime event to be triggered(https://uptest-sc.github.io/cli/watch_runtime_upgrade.html)
• 3: execute the XCM call and verify that it worked(someone could use libuptest to just schedule the XCM calls after the runtime upgrade is finished)
• 4: verify that the xcm call was executed on sender and receiver chain(not implemented)

We do not have any XCM functionality doe, however this could be achieved with subxt that libuptest is compatible with. It could also just use some after runtime upgrade scheduling functionality and execute a subxt pallet call extrinsic. Step 4 remains unimplemented.

[flipchan]

XCM call verifier needs to be implemented