Polyfill fetch Headers api

[whatyoubendoing]

Description

The global Headers object is missing and needs to be poly-filled. This object is essential for interacting with the Fetch API. Without it, packages or code that depend on Headers are more likely to encounter errors.

Steps To Reproduce

1. Add new Headers() to any extension command.
2. Run the command

Current Behaviour

Throws an error

ReferenceError: Headers is not defined

Expected Behaviour

Should not throw an error.