chore: fine grained tracing

[IWANABETHATGUY]

Related issue (if exists)

#2989, not sure if we could close that.

Summary

1. Before we could only use TRACE, INFO, etc, to enable tracing . The method we used before has a pitfall, we can't did some fine-grained event filter, for example, only emit the event in function rspack_core::compiler::compilation:xxxx. This might be a problem when you are trying to debug a big project which might have thousands of modules, the tracing file would be too long to read.
2. After this pull request, we could use the same syntax supported by Tokio tracing https://docs.rs/tracing-subscriber/latest/tracing_subscriber/filter/struct.EnvFilter.html#directives. when you want to trace all debug event in rspack emitted by rspack* crate, you could use

TRACE=info cargo rb bench -F tracing &| sed -e 's/\x1b\[[0-9;]*m//g' > result.log   

or for javascript

TRACE=info npx rspack build

If you only care about event in mod rspack_core::compiler::compilation you could use

TRACE=rspack_core::compiler::compilation cargo rb bench -F tracing &| sed -e 's/\x1b\[[0-9;]*m//g' > result.log   

🤖 Generated by Copilot at 50acdb1

This pull request improves the tracing functionality for the bench and rspack_tracing crates. It allows the bench crate to select different tracing output formats by setting an environment variable. It also simplifies the tracing configuration and output in the rspack_tracing crate by using the EnvFilter layer.

Walkthrough

🤖 Generated by Copilot at 50acdb1

• Add Layer enum to control tracing output format (link)
• Import FromStr trait to implement Layer enum (link)
• Modify run function to take layer parameter and pass it to tracing initialization functions (link)
• Return Option<FlushGuard> from tracing initialization functions to flush output when out of scope (link, link)
• Simplify tracing enabling condition by checking only TRACE environment variable (link)
• Use EnvFilter layer to allow user to specify target and level filters by environment variable (link)
• Remove #[cfg(feature = "tracing")] attribute and always enable tracing feature (link)
• Fix typo in smoke-example/basic path (link)

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Latest commit: cc2e630

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