Nicer asset filenames

[lensbart]

Hello,

For some generated files, such as JavaScript chunk files, the file name really doesn’t matter. However, other files, such as assets used for images, are more likely to be downloaded by some users. For these files, it would be nice if the file name remained as chosen by the developer, and cache busting would be implemented by putting the hash in a directory name instead of the file name.

For example, when I import avatar from './user.jpg' and then <img alt="always use alt lol" src={avatar} />, the image will be located at e.g. public/build/_assets/user-NOEI2W6T.jpg and the browser will suggest the file name user-NOEI2W6T.jpg when the user right-clicks to download the image. I think a neater solution would be to put this file in public/build/_assets/NOEI2W6T/user.jpg instead, preserving the original filename.