Add Unknown license to Scan Result Policies

What does this MR do and why?

This MR adds new special type of license unknown that is returned when the scanner is not able to find valid license name. We need to add this to allow users to create policies based on this.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Create new project
2. Go to Secure -> Policies
3. Create new policy -> Select Scan Result Policy
4. Select License Scan policy and go to License is Matching dropdown and try to look for Unknown license

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #411984 (closed)