wasmer 4.x support

[chancehudson]

This PR bumps the wasmer version from 2.x to 4.x. This relies on updates to the circom-compat repo to support this version (implemented in the fork here).

Related #151

[vivianjeng]

There is a good implementation example here
https://github.com/l-adic/circom-compat
but for iOS we still need to patch the wasmer like
wasmerio/wasmer@09c7070

I haven't tried either if we patched the wasmer it works for iOS
or if it can be published in testflight #107

[vivianjeng]

You can also fork the latest wasmer in zkmopro and patch these lines

[chancehudson]

@vivianjeng I think this is ready for review now. I removed the singleton pattern that was caching the wasm executor because of changes in wasmer@4. There's an in memory Store that tracks execution of the wasm and needs to be mutable so it can't be in a static singleton.

The new wasmer also relies more on async functions so tests are async.

[vivianjeng]

I tried to run it on iOS
Now it can be run if the device is connected to xcode
but it cannot be run if the device is disconnected to xcode
(you download the app, stop xcode, and open the app again and run)

Previously we use dylib feature to fix this
but I tried to use dylib, it throws

error: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/install_name_tool: input file: /Users/zhengyawen/Documents/GitHub/vimwitch/mopro/mopro-example-app/target/aarch64-apple-ios/release/multiplier2.dylib is not a Mach-O file

Not sure if the wasmer is wrong
but in wasmer v4, there is no dylib feature

I saw there is also a solution like https://github.com/oliveeyay/SwiftWasmer
wasmerio/wasmer#4343
I am not sure if it works in our case

Do you know if the dylib feature can be fixed?
Is it possible that it can be run when disconnected to xcode?

[chancehudson]

Closing in favor of #179