refactor(eas-cli): use built-in Node fetch instead of undici

[byCedric]

Why

This is a follow-up PR of #2414, to try and fall-back to the built-in Node fetch support as much as possible. This is an attempt, as likely more things will pop up that require refactoring.

Unfortunately, we still require undici as advanced "non-spec" features are used, like import { ProxyAgent } from 'undici'. But, this tries to use all built-in features as much as possible.

How

• Re-exported Node fetch globals instead from undici
  • Dropped the nock workaround from refactor(eas-cli): swap node-fetch for undici to support Node 22 better #2414 as well
• TBD

Test Plan

See GitHub Actions, and manual testing (everything)

[github-actions]

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