Fixes https://github.com/bevyengine/bevy/issues/9458.
On case-insensitive filesystems (Windows, Mac, NTFS mounted in Linux,
etc.), a path can be represented in a multiple ways:
- `c:\users\user\rust\assets\hello\world`
- `c:/users/user/rust/assets/hello/world`
- `C:\USERS\USER\rust\assets\hello\world`
If user specifies a path variant that doesn't match asset folder path
bevy calculates, `path.strip_prefix()` will fail, as demonstrated below:
```rs
dbg!(Path::new("c:/foo/bar/baz").strip_prefix("c:/foo"));
// Ok("bar/baz")
dbg!(Path::new("c:/FOO/bar/baz").strip_prefix("c:/foo"));
// StripPrefixError(())
```
This commit rewrites the code in question in a way that prefix stripping
is no longer necessary.
I've tested with the following paths on my computer:
```rs
let res = asset_server.load_folder("C:\\Users\\user\\rust\\assets\\foo\\bar");
dbg!(res);
let res = asset_server.load_folder("c:\\users\\user\\rust\\assets\\foo\\bar");
dbg!(res);
let res = asset_server.load_folder("C:/Users/user/rust/assets/foo/bar");
dbg!(res);
```
94c67afa4b