Add --wasm-debug flag

[paul-hansen]

Summary

This adds a --wasm-debug flag which enables embedding DWARF debug info and rust's normal debug info to enable source maps in the Wasm file.

This can be used by browsers to show the file and line numbers in backtraces and use the Rust source in debuggers.

How to use

Currently I've only figured out how to use this with Chrome (lmk if anyone gets it working with Firefox!)

• Make sure your project uses console_error_panic_hook (if you used a Leptos template it should already)
• Install the C/C++ devtools support (DWARF) extension.
• Restart Chrome
• Make sure cargo-leptos is updated

  cargo install cargo-leptos --locked --force
  

• Run your project with the new flag

  cargo leptos watch --wasm-debug
  

Warning

Make sure you haven't disabled Rust's debug symbols, don't forget to check your global ~/.cargo/config.toml.
If you don't see debuginfo when your build finishes e.g. Finished dev [unoptimized + debuginfo] target(s), you will need to re-enable this.

• Open your project in chrome and do something that causes a panic in your Rust code (can just add a panic in one of your components. The second error message should now have clickable links to the Rust files instead of the wasm symbols.
  

This blog post goes over most of these steps with more detail/pictures: https://developer.chrome.com/blog/wasm-debugging-2020/

[paul-hansen]

Note: If we wanted we could split these up into two flags, but I think most people will want to enable both. If you enable keep_debug but not debug you get file names in stack traces but clicking them no longer opens the Rust source files.

[paul-hansen]

CI failures should be fixed. Ran cargo insta review to accept the changes to the config snapshots. Also rebased on latest main again just for good measure.
cargo test --features=full_tests is now passing locally.

[benwis]

This all looks good, the last failure is a missing param in a windows test.