Add node-fetch extensions typing

[shinyaohira]

• follow
• timeout
• compress
• size
• agent

to RequestInit interface. See node-fetch README.
I think we need these options for production services.

TODO:

• Update CHANGELOG.md with your change (include reference to issue & this PR)
• Make sure all of the significant new logic is covered by tests
• Rebase your changes on master so that they can be merged easily
• Make sure all tests and linter rules pass

[apollo-cla]

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