Added default fields for DNS requests

[Ice3man543]

Proposed changes

Checklist

Closes #1205

• Pull request is created against the dev branch
• All checks passed (lint, unit/integration/regression tests etc.) with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)

[ehsandeep]

echo docs.hackerone.com | ./nuclei -t a.yaml 

                     __     _
   ____  __  _______/ /__  (_)
  / __ \/ / / / ___/ / _ \/ /
 / / / / /_/ / /__/ /  __/ /
/_/ /_/\__,_/\___/_/\___/_/   2.5.4-dev

		projectdiscovery.io

[WRN] Use with caution. You are responsible for your actions.
[WRN] Developers assume no liability and are not responsible for any misuse or damage.
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x2 addr=0x0 pc=0x104dae86c]

goroutine 1 [running]:
github.com/projectdiscovery/nuclei/v2/pkg/protocols/dns.(*Request).Compile(0x140000148c0, 0x140004868c0)
	/Users/geekboy/Github/nuclei/v2/pkg/protocols/dns/dns.go:106 +0x3c
github.com/projectdiscovery/nuclei/v2/pkg/protocols/common/executer.(*Executer).Compile(0x1400043dc60)
	/Users/geekboy/Github/nuclei/v2/pkg/protocols/common/executer/executer.go:28 +0x80
github.com/projectdiscovery/nuclei/v2/pkg/templates.Parse({0x14000378440, 0x31}, {0x0, 0x0}, {{0x0, 0x0}, {0x0, 0x0}, {{0x0, 0x0}, ...}, ...})
	/Users/geekboy/Github/nuclei/v2/pkg/templates/compile.go:92 +0x4e0
github.com/projectdiscovery/nuclei/v2/pkg/catalog/loader.(*Store).LoadTemplates(0x140001523f0, {0x140000706d0, 0x1, 0x1})
	/Users/geekboy/Github/nuclei/v2/pkg/catalog/loader/loader.go:215 +0x34c
github.com/projectdiscovery/nuclei/v2/pkg/catalog/loader.(*Store).Load(0x140001523f0)
	/Users/geekboy/Github/nuclei/v2/pkg/catalog/loader/loader.go:137 +0x40
github.com/projectdiscovery/nuclei/v2/internal/runner.(*Runner).RunEnumeration(0x14000152090)
	/Users/geekboy/Github/nuclei/v2/internal/runner/runner.go:272 +0x83c
main.main()
	/Users/geekboy/Github/nuclei/v2/cmd/nuclei/main.go:33 +0x18c

id: test

info:
  name: test
  author: pdteam
  severity: info

dns:
  - name: "{{FQDN}}"
    type: A

    extractors:
      - type: regex
        group: 1
        regex:
          - "IN\tCNAME\t(.+)"