[feat] tracing support for rust webviews (leptos, yew etc.)

This is a feature offer rather than a feature request!

I have implemented a subscriber layer for passing tracing events created with the standard tracing macros (`error!`, `warning!` etc.) and instrumentation to either the `tauri_plugin_log` endpoint, a tracing specific endpoint and/or the web-console. If interested, I could offer a PR.

**Motivation**

I use `tracing` for it's spans, filtering and structured data. I have my own tracing formatters so would prefer not to use `log` as supported by `tauri_plugin_log`.

It's possible to integrate tracing and log with `tracing-log` but it means losing features/support and it has undesirable consequences like forcing execution of all event code even if disabled.

**Options**

1. If it's not wanted or already exists, you can just close this issue

2. As a feature of `tauri_plugin_log` allowing a user to switch between tracing and log

3. As it's own `tauri_plugin_tracing`

a) as an official tauri plug-in
b) as an independent crate (is there a naming scheme for unofficial plugins?)

**guest-rust**

Some plug-ins have `guest-js` for client integration but I haven't seen the equivalent for rust webview integration i.e. `guest-rust` which is necessary in this case. This could be as a separate crate or as a feature on the plug-in crate e.g. `webview` or something. Ideally there is a standardised pattern for this.