feat: option to create instance in another thread/process

[predatorx7]

Description

All JS Execution environments on iOS/MacOS is maybe created on the same thread, add an option for making it on a new thread instead

Requirements

• Add an option for making the underlying JS execution environment on a new thread

Additional Context

Refer: https://developer.apple.com/documentation/javascriptcore/jsvirtualmachine#Support-Threading-and-Concurrent-JavaScript-Execution

[predatorx7]

Created this because I noticed a -10% performance difference when using ~2 JS runtimes with continuous JS code execution compared to running similar JS code in headless webviews on iOS.

(Also causes eventual freezing on higher loads)