Add WASM module to build robot identities on the client about robosats

[Reckless-Satoshi]

There is some progress:
Here the robo-identities cargo workspace https://github.com/reckless-satoshi/robo-identities
The robo-identities-wasm is 760KB (Robohash avatar generator only) or 1.1MB robohash and nickname generator.

The robohash generator contains all of the robot parts, so having the .wasm is the only asset needed for the client to generator robots. It can generate up to 1,293,692,400 different robots, which is quite a lot more than the original RoboHash. This is due to the fact that the color is programmatically computed via hue rotation (359 variants), instead of sticking to the same 8 colors of the .png files (was also needed to save of size).

Here the WIP PR to integrate it into RoboSats app #735 . Given that computing an avatar takes ~200ms, computing all avatars in the book is blocking rendering. Therefore, the avatar generation is moved to webworkers. It works like a charm, and avatars can be generated and cached even before the book is opened.

Unfortunately, it does not work on the Android Webview app, I am looking for fixes, but possibly is an issue with the relative paths in Android... might be solved by inlining the webworker and wasm.

[secondl1ght]

Great progress, looking forward to trying it out!