Support local image uris

[mlynch]

We need to support loading/showing images from local URIs in order to avoid possible memory issues that can occur when fetching images with the Filesystem APIs that return base64 strings.

Since we don't support file:// we will probably want a custom scheme we can parse in the webserver and return data to, perhaps capacitor://

[mlynch]

Sounds like we do have this support already, but I wonder if we could make it more seamless