v7 Roadmap + Planning

This ticket represents the tasks we're planning to include as part of the v7 release of `@globus/sdk`.

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- [ ] Update all method signatures to **only** accept new, single, parameter object.
- We've slowly been adding `next` member exports to services that provide access to these new signatures (e.g., `search.query.next.get({ request: { query: { q: 'example' } } })`. In v7, these new signatures will replace all exported members.

- [ ] Drop support for Node 20; End-of-life April 30, 2026.
- [ ] Remove `cross-fetch` dependency.

- [ ] Write migration guide.