Add support for static Response.json method

[Cherry]

This was recently added to the Workers runtime: https://community.cloudflare.com/t/2022-5-26-workers-runtime-release-notes/386584

Other references:

• Add Response.json static method whatwg/fetch#1392
• Updated spec: https://fetch.spec.whatwg.org/#response-class

undici 5.3.0 added support for this, so updating to the newer version of undici may resolve this. I briefly attempted this but was met with about ~40 test failures that were a little beyond my scope of understanding for this repo. 😅

[mrbbot]

Hey! I've just released version 2.5.0 with support for this method.