fix panic when more than one proxy is given as input

[tarunKoyalwar]

Proposed changes

• fix send on closed channel when more than 1 proxy is given in input
• use utils/proxy to preprocess proxies before using adds proxy utils utils#126
• closes Crash with proxy input (panic: send on closed channel) #3513

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)

[tarunKoyalwar]

Public Proxies proxies.txt

POC

$  go run -race  . -u scanme.sh   -proxy ~/test-templates/proxies.txt -id "tech-detect"  -v

                     __     _
   ____  __  _______/ /__  (_)
  / __ \/ / / / ___/ / _ \/ /
 / / / / /_/ / /__/ /  __/ /
/_/ /_/\__,_/\___/_/\___/_/   v2.9.2-dev

		projectdiscovery.io
[VER] Using http://5.189.184.6:80 as proxy server
...redacted...
[INF] Using Nuclei Engine 2.9.2-dev (development)
[INF] Using Nuclei Templates 9.4.2 (latest)
[INF] Templates added in last update: 78
[INF] Templates loaded for scan: 1
[INF] Targets loaded for scan: 1
[INF] Running httpx on input host
[INF] Found 1 URL from httpx
[INF] No results found. Better luck next time!