Integrate tracing (#6339)

Tracing Integration
- [reference](5bbf1859e9/projects/project-ideas.md (L297))


  - [x] replace slog & log with tracing throughout the codebase
- [x] implement custom crit log
- [x] make relevant changes in the formatter
- [x] replace sloggers
- [x] re-write SSE logging components

cc: @macladson @eserilev

testing/ef_tests/src/cases/fork_choice.rs

@@ -371,7 +371,6 @@ impl<E: EthSpec> Tester<E> {
         }
 
         let harness = BeaconChainHarness::<EphemeralHarnessType<E>>::builder(E::default())
-            .logger(logging::test_logger())
             .spec(spec.clone())
             .keypairs(vec![])
             .chain_config(ChainConfig {