Experiment with funds sourcing logic

[shekhirin]

Currently, we query all supported chains for the asset we're interested in, wait for responses, and source funds starting from highest balances

relay/src/rpc/relay.rs

Lines 1237 to 1238 in d9181d8

	// highest balances first
	sources.sort_unstable_by(|a, b| b.2.cmp(&a.2));

This requires us to wait for slower RPCs, such as Arbitrum, but we could also limit our waiting to say 50ms and get highest balance from those who replied. An obvious issue is that we'll first drain faster RPCs.