Added http probing to clustering + add disable-clustering flag

[Ice3man543]

Proposed changes

Fixes #3020 + Added disable-clustering flag

./nuclei -h dc
Nuclei is a fast, template based vulnerability scanner focusing
on extensive configurability, massive extensibility and ease of use.

Usage:
  ./nuclei [flags]

Flags:
   -dc, -disable-clustering  disable clustering of requests

Checklist

• 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)