Execute external libraries in a sandbox only

[danimoh]

Run "external" libraries like BitcoinJS or ethers and OpenGSN in a sandboxed iframe with very restricted permissions to fence them off from access to the network, the Keyguard's databases, user interfaces, etc. Communication with the libraries would then happen via a postMessage api.
This would significantly reduce the risk of security bugs or potential malicious code in the libraries and removes the need for the libraries and the build tools we use to build them to be trusted.