test: migrate to node test runner

[ilteoood]

Checklist

• run npm run test and npm run benchmark
• 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

[dancastillo]

do we need deepStrictEqual on assertions rather than strictEqual?

[Eomm]

There is this failure on win:

not ok 40 - Should expose websocket and http route
  ---
  duration_ms: 19.3431
  location: 'D:\\a\\fastify-websocket\\fastify-websocket\\test\\router.test.js:98:1'
  failureType: 'testCodeFailure'
  error: 'plan expected 4 assertions but received 3'
  code: 'ERR_TEST_FAILURE'
  ...

could you check it?

[mcollina]

lgtm