CTS doesn't build with typescript 6 beta

[greggman]

I'm not sure what changes are needed but in testing PR #4599 it's clear some things will need updating. That change didn't break anything but trying to upgrade to ts6 did.

• we might need to update to the latest eslint which is requires changing configuration file formats
• we need to make sure dawn.node (and wgpu/deno) still work.
• may need to switch to .mjs or type: "module" to be more forward proof?