Support cypress.config.mts

[lmiller1990]

What would you like?

mts (which is ESM using TS extension) is a thing now, and we should support it, eg cypress.config.mts.

Docs: https://www.typescriptlang.org/docs/handbook/esm-node.html#new-file-extensions

Not sure of the implications here, in general mts will be compiled to mjs, and cts to cjs.

Why is this needed?

Support a format that is becoming more widely used.

Other

Node.js module system is quite confusing, make sure to add tests here https://github.com/cypress-io/cypress/blob/develop/system-tests/test/config_modules_spec.ts