Support loading images from AssetManager

[coil-kt]

Support loading images from AssetManager

[colinrtwhite]

Interesting! imageView.load(String) is currently reserved for HTTP URLs, but we should at least support imageView.load(Uri.parse("file:///android_asset/starrynight.jpg")). I think we could make the necessary changes in UriFetcher. I'll make a quick PR.

[ianhanniballake]

load(Uri) support would be great, thanks!

It seems like in other image loading libraries, load(uri: String) = load(Uri.parse(uri)) in all cases and they share the same underlying processing. This ensures that no matter if developers use a String or Uri, the same rules apply, avoiding all cases where developers need to remember to htmlUri.toString() or Uri.parse(contentUriString). Probably worth a separate FR than this as that would be a wider issue than this particular case.

[colinrtwhite]

Good point. Currently, Coil uses url as the named param for load(String) so we'd have to change that to something more general (but hopefully not too general like data; let me know if you have suggestions), but I like the idea of supporting Uris and Urls via load(String).

We could support this by writing a new Mapper or modifying HttpUrlMapper.

[colinrtwhite]

Created a new issue to support parsing Strings as Uris here: #24