Port gateway-block, gateway-car, and gateway-ipns-record tests to this suite

[laurentsenta]

After talking with @lidel these are excellent candidates for the conformance test suite:

• https://github.com/ipfs/kubo/blob/master/test/sharness/t0117-gateway-block.sh
• https://github.com/ipfs/kubo/blob/master/test/sharness/t0118-gateway-car.sh
  • Add dnslink support #22
  • Add ipns record support #10
• https://github.com/ipfs/kubo/blob/master/test/sharness/t0124-gateway-ipns-record.sh