feat: add cli support to build assets from executable (#3429)

* feat: add cli support to build assets from executable

See https://github.com/DioxusLabs/dioxus/discussions/3402#discussioncomment-11632372

* fix: store relative paths in executable

* bring back deprecation warning

---------

Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

packages/manganis/manganis-core/src/asset.rs

@@ -48,7 +48,7 @@ impl BundledAsset {
     /// Create a new asset but with a relative path
     ///
     /// This method is deprecated and will be removed in a future release.
-    #[deprecated(
+   #[deprecated(
         note = "Relative asset!() paths are not supported. Use a path like `/assets/myfile.png` instead of `./assets/myfile.png`"
     )]
     pub const fn new_relative(