feat(remix-testing)!: use type aliases instead of interfaces

[MichaelDeBoey]

Just like I did in #7363, #7366, #7367 & #7368

To transition more smoothly, we can start with exporting these public types with a V3_ prefix

This would be something like

export interface RemixStubProps {
  // ...
}
export type V3_RemixStubProps = RemixStubProps;

[changeset-bot]

🦋 Changeset detected

Latest commit: 83deeed

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 16 packages

Name	Type
@remix-run/testing	Major
create-remix	Major
remix	Major
@remix-run/architect	Major
@remix-run/cloudflare	Major
@remix-run/cloudflare-pages	Major
@remix-run/cloudflare-workers	Major
@remix-run/css-bundle	Major
@remix-run/deno	Major
@remix-run/dev	Major
@remix-run/eslint-config	Major
@remix-run/express	Major
@remix-run/node	Major
@remix-run/react	Major
@remix-run/serve	Major
@remix-run/server-runtime	Major

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[brophdawg11]

Closing per #7362 (comment)