Reusing dynamically extracted values as iterators in http request

[Ice3man543]

This PR adds the support in http module to iterate over the dynamically extracted data from extractors
and use it in other requests. This allows nuclei to follow links on pages, do operations with
multiple versions of the same extracted value, etc.

Proposed changes

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)

[Ice3man543]

Example Template

id: valid-robotstxt-endpoints

info:
  name: Iterate robots.txt and request endpoints
  author: pdteam
  severity: info

requests:
  - raw:
      - |
        GET /robots.txt HTTP/1.1
        Host: {{Hostname}}

      - |
        GET {{endpoint}} HTTP/1.1
        Host: {{Hostname}}

    iterate-all: true
    extractors:
      - part: body
        name: endpoint
        internal: true
        type: regex
        regex:
          - "(?m)/([a-zA-Z0-9-_/\\\\]+)"

    matchers:
      - type: status
        status:
          - 200

To test -

 ./nuclei -t test.yaml -u https://github.com

./nuclei -t test.yaml -u https://github.com

                     __     _
   ____  __  _______/ /__  (_)
  / __ \/ / / / ___/ / _ \/ /
 / / / / /_/ / /__/ /  __/ /
/_/ /_/\__,_/\___/_/\___/_/   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.
[INF] Using Nuclei Engine 2.5.4-dev (development)
[INF] Using Nuclei Templates 8.6.8 (latest)
[INF] Using Interactsh Server https://interactsh.com
[INF] Templates added in last update: 0
[INF] Templates loaded for scan: 1
[valid-robotstxt-endpoints] [http] [info] https://github.com/robots.txt
[valid-robotstxt-endpoints] [http] [info] https://github.com/search/advanced
[valid-robotstxt-endpoints] [http] [info] https://github.com/account-login
[valid-robotstxt-endpoints] [http] [info] https://github.com/stargazers
[valid-robotstxt-endpoints] [http] [info] https://github.com/archive/
[valid-robotstxt-endpoints] [http] [info] https://github.com/tarball/
[valid-robotstxt-endpoints] [http] [info] https://github.com/contributors
[valid-robotstxt-endpoints] [http] [info] https://github.com/pulse
[valid-robotstxt-endpoints] [http] [info] https://github.com/tags
[valid-robotstxt-endpoints] [http] [info] https://github.com/zipball/
[valid-robotstxt-endpoints] [http] [info] https://github.com/Explodingstuff/
[valid-robotstxt-endpoints] [http] [info] https://github.com/forks
[valid-robotstxt-endpoints] [http] [info] https://github.com/search
[valid-robotstxt-endpoints] [http] [info] https://github.com/watchers
[valid-robotstxt-endpoints] [http] [info] https://github.com/ekansa/Open-Context-Data
[valid-robotstxt-endpoints] [http] [info] https://github.com//docs
[valid-robotstxt-endpoints] [http] [info] https://github.com/download
[valid-robotstxt-endpoints] [http] [info] https://github.com/revisions

[Mzack9999]

Looks good:

• Interactsh test failure can be ignored
• Marking as request changes due to conflicts