Update report format to allow url links with the ftp protocol

What does this MR do?

This MR allows reports to have URLs associated with the vulnerability that are prefixed with ftp:// instead of only allowing http:// and https://.

What are the relevant issue numbers?

Container scanning result parsing can fail if u... (gitlab-org/gitlab#404641 - closed)

Checklist

• Ensure changes can be built upon without requiring a breaking change, see Building for Extensibility.
• Review and add/update tests for this feature/bug.
• Add an entry to the CHANGELOG if required, with the appropriate version. See Classifying Changes.
• Assign the MR to the appropriate person/people for review.