Implement tracing::Event handling & parent_id for spans and events (#6672)

* implement events handling, implement parent_id for spans & events

* add events to sp_io::storage

* update test

* add tests

* adjust limit

* let tracing crate handle parent_ids

* re-enable current-id tracking

* add test for threads with CurrentSpan

* fix log level

* remove redundant check for non wasm traces

* remove duplicate definition in test

* Adding conditional events API

* prefer explicit parent_id over current,

enhance test

* limit changes to client::tracing event implementation

* remove From impl due to fallback required on parent_id

* implement SPAN_LIMIT

change event log output

* change version of tracing-core

* update dependancies

* revert limit

* remove duplicate dependency

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

Co-authored-by: Matt Rutherford <mattrutherford@users.noreply.github.com>
Co-authored-by: Benjamin Kampmann <ben@parity.io>
Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/client/executor/src/integration_tests/mod.rs

@@ -661,7 +661,8 @@ fn parallel_execution(wasm_method: WasmExecutionMethod) {
 fn wasm_tracing_should_work(wasm_method: WasmExecutionMethod) {
 
 	use std::sync::{Arc, Mutex};
-	use sc_tracing::SpanDatum;
+
+	use sc_tracing::{SpanDatum, TraceEvent};
 
 	struct TestTraceHandler(Arc<Mutex<Vec<SpanDatum>>>);
 
@@ -669,6 +670,8 @@ fn wasm_tracing_should_work(wasm_method: WasmExecutionMethod) {
 		fn handle_span(&self, sd: SpanDatum) {
 			self.0.lock().unwrap().push(sd);
 		}
+
+		fn handle_event(&self, _event: TraceEvent) {}
 	}
 
 	let traces = Arc::new(Mutex::new(Vec::new()));