eip-0028 ErgoAuth

I've encountered a couple roadblocks while developing for eip-28

### Mobile issues
- Ergoauth doesn't return to the authenticating website once the message is signed. (It does return on an Ergopay request)
- No way to generate the required SigmaBoolean without running appkit. Shouldn't it just accept a normal address string? Why does it need to be converted to a SigmaBoolen first? I can't find a way to do this in `ergo-lib-wasm-nodejs` or `fleetsdk`, though I'd be happily proven wrong. I couldn't figure it out by going through the `sigmastate` source files which have the functions that appkit uses, but if someone would show me the correct function, I'll build a typescript version.

### Inconsistencies
There should be a consistent signature string returned. It doesn't matter which is chosen, but a standard would be helpful so we don't need to filter for wallet type first.

For reference: mobile returns 20 random characters, then the provided message, then the address WITH `https://` followed by 20 more random characters. Nautilus returns the provided message, a semi-colon, the source address WITHOUT `https://`, another semi-colon, followed by two strings of random characters separated by a semi-colon.