[portis-web3] Move away from web3-provider-engine

[bpierre]

@portis/web3 uses a fork of web3-provider-engine, which is not actively maintained anymore.

web3-provider-engine also relies outdated dependencies and on native Node modules, which means that using @portis/web3 requires bundlers to provide Node polyfills at the moment. It means that trying to use this library with a bundler like Webpack 5 or Snowpack won’t work without custom tweaks.

A solution could be to use eth-provider which is actively maintained and also much smaller than web3-provider-engine (7.1kb vs. 82.4kb).

Related discussion in the WalletConnect repository: WalletConnect/walletconnect-monorepo#310