Provide example projects for supported Dependency Scanning targets

Problem to solve

As times, users will contact support asking why scanning for their project (e.g. Gradle) isn't working.

The support team, then needs to setup their own projects in order to demonstrate a working scenario, and from there work with the user to determine what's wrong in their setup.

Proposal

Provide a number of public projects in https://gitlab.com/gitlab-examples/security/ that provide example coverage for all languages/frameworks that we support in SCA:Dependency Scanning.