Importing raw camera photos #2188

A partial implementation in #2106 but is blocked. This is the final deliverable from a Google Summer of Code project.

This work was stalled because it was unusable due to memory restrictions #1895.

This will be solved by reducing copying of image data as much as possible via the asset database system (#1604). Further, we can save the actual data in JS memory and read it from Wasm memory.

Other possible solutions:

• Reducing copying of image data using Arc<Image>.
• Using memory64 if it is released as stable in Chrome, Firefox, and Safari.
• Somehow reducing the memory requirements of autosave (e.g. don't encode the uncompressed f32 values as base64). Possibly addressed as part of Asset database #1604.