feat: Add PuttyPrivateKey rule and allowlist for raw content

[baruchiro]

Description:

PuTTY is a common SSH and telnet client for Windows. It installed with a "PuTTY Key Generator, which is generating a regular private/public keys, but saves them in a different format.

To support this, I added support for apply the AllowList.Regexes on the fragment.Raw content.

I also added a validateFragment to validate a rule that accept the Path field.

Checklist:

• Does your PR pass tests?
• Have you written new tests for your changes?
• Have you lint your code locally prior to submission?

Original: gitleaks#1373