Macro decl_test_network

macro_rules! decl_test_network {
    (
		pub struct $name:ident {
			relay_chain = $relay_chain:ty,
			parachains = vec![ $( ($para_id:expr, $parachain:ty), )* ],
		}
	) => { ... };
}

Declares a test network that consists of a relay chain and multiple parachains. Expects a network struct as an argument and implements testing functionality, ParachainXcmRouter and the RelayChainXcmRouter. The struct needs to contain the relay chain struct and an indexed list of parachains that are going to be in the network.

decl_test_network! {
	    pub struct ExampleNet {
	        relay_chain = Relay,
	        parachains = vec![
	            (1, ParaA),
	            (2, ParaB),
	        ],
	    }
}