Add regexp pattern for template-id

[zerodivisi0n]

Do I understand correctly that this is enough to fix #276?
These changes produce the following json schema output in nuclei-jsonschema.json:

"id": {
  "pattern": "^(?:[a-zA-Z0-9][a-zA-Z0-9]*-?[a-zA-Z0-9]+?)+$",
  "type": "string",
  "title": "id of the template",
  "description": "The Unique ID for the template",
  "examples": [
    "cve-2021-19520"
  ]
}

[ehsandeep]

@zerodivisi0n can we also include support for underscore (_)?

[forgedhallpass]

Do I understand correctly that this is enough to fix #276?

@zerodivisi0n

1. I don't think it's enough, but you can test it out easily. Just modify a template ID and run nuclei with the validate flag against it. The change would also require a unit test.
2. The JSON Schema is only used for template development in an IDE context. If the pattern field is supported, you should be able to see the ID underlined/highlighted, notifying that there is a validation error.

[forgedhallpass]

see my comment in the conversation

[zerodivisi0n]

• Updated regexp to a simpler one
• Added a custom validation code as the simplest solution because the current jsonschema module does not support validation
• Added some tests for the parser

[Ice3man543]

Thanks for the PR @zerodivisi0n. Merged it.