* fix: handle multiple cookies in streaming responses
This fix does address that cookies have to be handled
specially in lambda responses.
Fixes #2921
* test: check cookie handling
* test(vitest): replace `jest` with `vitest` for core tests
* test(fastly): `jest` -> `vitest`, correct env for fastly
* test(jest): remove `jest-environment-miniflare` as dep
* test(lagon): configure `lagon` tests to run on `vitest`
* test(lambda): `jest` -> `vitest`
* test(lambda-edge): `jest` -> `vitest`
* test(node): `jest` -> `vitest`
* test(wrangler): `jest` -> `vitest`
* chore(deps): remove `jest` and `ts-jest` from deps
* test(vitest): add `yarn coverage` for checking coverage
* test(fastly): fix check for `globalThis.crypto`
* test(handler): fix stray `.only`
* test(lagon): change env file back to original path
* test(fastly): go back to `jest` until `vitest` has support for fastly env
* test(fastly): remove hack for the `crypto` global from the test
