[Feature] Add test helper for tracestorage subscriber

[mattsse]

Component

other

Describe the feature you would like

op-alloy/crates/protocol/src/batch/span.rs

Lines 633 to 635 in 2a70833

	let trace_store: TraceStorage = Default::default();
	let layer = CollectingLayer::new(trace_store.clone());
	tracing_subscriber::Registry::default().with(layer).init();

this doesn't work in regular cargo test because this uses the global tracing dispatcher and will panic if already configured

Additional context

No response

[emhane]

closing in favour of op-rs/maili#22