Fix missing template_url for pd signed templates

[RamanaReddy0M]

• Fixes missing template_url for pd signed templates when executed from custom path.

• closes [BUG] json outputs and exports missing encoded templates #5643

Test cmd:

 ✗ ./nuclei -t ~/custom-dir/nuclei-templates/http/technologies/wordpress-detect.yaml -u www.sonymusic.com -j -silent | jq '.["template-url"]'

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)