Implementation of ISigner for web3auth

[sneakzttv]

Talking to Oleksandr today to figure this one out and will create a pr once done.

[Arshia001]

Hey team! Please add your planning poker estimate with Zenhub @oleksandrchainsafe @RyRy79261 @sneakzttv

[KBryan]

IEvmSigner interface is being used with Unity waiting on outstanding PR before moving forward.

[janegabitova]

23-06-23: prefabs on the client side left over; no longer blocked. to finalize next week

[alexvotofuture]

Kwame is mostly wrapped up with this, and it works with new architecture as expected. Just cleanup now - should be ready to test by end of day - testing to happen next week.

[KBryan]

https://github.com/ChainSafe/web3.unity/pull/508

[Arshia001]

Since we need additional Nethereum libs to make this work, we should be putting code in the publish-to-unity-* scripts to actually copy the DLLs from the libraries folder to the UPM package folder.

[kalambet]

Fixed in #534