Add workflow which verifies that the node is producing blocks

[maltekliemann]

#683 demonstrates that our testing happens in a vacuum. We should add a test which (at the very least) verifies that the node is capable of producing blocks and responds to RPC.

(This could be done just by adding integration tests.)

[sea212]

We have block production tests using Chopsticks, #917, however it would be still very useful to see whether:

1. The client connects to a live network and syncs block (can use rpc to see if best block changes within a couple of minutes)
2. The list of known RPCs works
3. No memory leak exists.

[maltekliemann]

@sea212 @Chralt98 bump

Should also verify that transactions can be sent.

[sea212]

Solved in #1194