Fix embedded watcher to work with external crates

[shanecelis]

Objective

Tried using "embedded_watcher" feature and embedded_asset!() from another crate. The assets embedded fine but were not "watched." The problem appears to be that checking for the feature was done inside the macro, so rather than checking if "embedded_watcher" was enabled for bevy, it would check if it was enabled for the current crate.

Solution

I extracted the checks for the "embedded_watcher" feature into its own function called watched_path(). No external changes.

Alternative Solution

An alternative fix would be to not do any feature checking in embedded_asset!() or an extracted function and always send the full_path to insert_asset() where it's promptly dropped when the feature isn't turned on. That would be simpler.

    ($app: ident, $source_path: expr, $path: expr) => {{
        let mut embedded = $app
            .world
            .resource_mut::<$crate::io::embedded::EmbeddedAssetRegistry>();
        let path = $crate::embedded_path!($source_path, $path);
        //#[cfg(feature = "embedded_watcher")]
        let full_path = std::path::Path::new(file!()).parent().unwrap().join($path);
        //#[cfg(not(feature = "embedded_watcher"))]
        //let full_path = std::path::PathBuf::new();
        embedded.insert_asset(full_path, &path, include_bytes!($path));
    }};

Changelog

Fix embedded_watcher feature to work with external crates