chore: move from tap to node:test

[eugleenyc]

These changes are related to the issue fastify/fastify#5555
Changed signer.test.js and cookie.test.js to use node:test instead of tap.

Checklist

• run npm run test
• tests and/or benchmarks are included
• documentation is changed or added
• commit message and code follows the Developer's Certification of Origin
  and the Code of conduct

[gurgunday]

LGTM

[dancastillo]

Can you use test context so assert.strictEqual -> t.assert.strictEqual

[dancastillo]

Can you add back in t.plan. The test will end before assertions are compelete i believe
Then for the tests with callbacks update to

test('test name here', (t, done) => {
  // set up and test code
  done() // call after last assertion
})

[jsumners]

Please address @dancastillo's concern.