Add training section (basic UI) to vulnerability details page

What does this MR do and why?

Add the training section to the vulnerability details page and make the feature flag available.

This MR is part of the new security training feature, please see the epic for details and the implementation breakdown > &6176 (closed)

Note the implementation of adding the training section is split into the following MR > (copied from here > #346066 (comment 802988533))

MR	Changes
Add training section (basic UI)	this MR
Connect graphql to display training section	TBD
Make API call to fetch training	TBD
Add loading status	TBD

Screenshots or screen recordings

How to set up and validate locally

This feature is behind a feature flag, to enable

rails c

Feature.enable(:secure_vulnerability_training)

1. Navigate to the Vulnerability report
2. Click on a vulnerability
3. You will see the training section

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 #346066 (closed)