[feat][v2] automatically rebuild webview-dist

[pronebird]

Describe the problem

Hi,

It seems that each time we change webview-src/index.ts we have to run npm run build manually to rebuild the webview-dist/index.d.ts.

Describe the solution you'd like

It would be great if tauri_plugin::Builder::new(COMMANDS).build() could automatically run npm run build when webview-src/*.ts contents change.

Alternatives considered

Modify build.rs and run npm run build manually, i.e:

const COMMANDS: &[&str] = &[ .. ];

fn main() {
    tauri_plugin::Builder::new(COMMANDS).build();

    println!("cargo:rerun-if-changed=webview-src");
    std::process::Command::new("npm")
        .arg("run")
        .arg("build")
        .spawn()
        .unwrap();
}

Additional context

No response

[amrbashir]

I don't think we should add this because plugin authors could choose 1 of infinite number of ways to build their plugin frontend code. The alternative way should be used or manually build when you need.