feature: Security Hub plugin

### 🔖 Feature description

AWS Security Hub provides you with a comprehensive view of your security state in AWS and helps you assess your AWS environment against security industry standards and best practices. There should be a plugin that provides the ability to view AWS Security Hub findings related to specific entities. This should be designed to display as an additional tab on the entity page (similar to CI/CD).

Information provided should consist of:
1. Table of findings
2. Potentially some aggregations by dimensions such as severity, AWS account, region

Screenshot of prototype:


### 🎤 Context

This would provide functionality similar to other security plugins such as:

https://github.com/deepan10/backstage-plugin-blackduck
https://github.com/snyk-tech-services/backstage-plugin-snyk

### ✌️ Possible Implementation

_No response_

Start by reviewing the repository's existing Backstage plugins and the linked Black Duck and Snyk plugin examples, then examine AWS Security Hub findings and entity-page integration. Done means an additional entity-page tab can display a findings table and, if supported by the design, aggregations by severity, AWS account, and region.

Written by the indexing model from the issue text.