Add SAST analyzer for Typescript

What does this MR do?

Adds the initial version of the tslint analyzer for running SAST scans on typescript projects. This uses the TSLint security plugin to test typescript code against 16 different security rules.

Huge thanks to @groulot for inspiration on analyzers/eslint, I was able to adapt the vast majority of his code to make this one straightforward.

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ee/issues/7158

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for GitLab EE, if necessary
• Documentation created/updated for this project, if necessary
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• [ ] Job definition updated, if necessary
  • [ ] Auto-DevOps template
  • [ ] Job definition example
  • [ ] CI Templates
• Conforms to the code review guidelines
• Conforms to the Go guidelines
• Security reports checked/validated by reviewer