CloudFormation StackSet - Ability to view all stack instance overridden parameters centrally

## 1. Title
AWS CloudFormation StackSet need ability to view stack details via centralized view such as overridden parameters.

## 2. Scope of request
Currently as you create a stack set with 10s of stacks it is very hard to see what each stack has been deployed with. i.e. what were the overridden parameters when deploying to those stacks. For a parameterized stack deployed via the stackset it can cause a lot of pain and management overhead.

## 3. Expected behavior

- Each Stack instance should hold the last overridden parameter set per stack instance so it is centrally viewable.
- Stackset should list all stacks with a link, or pop up or even list the overrides in line.
- Additionally if this was available via API calls / CLI then it would be great too for automation.

## 6. Category - CloudFormation

The issue names CloudFormation StackSets, stack instances, and API/CLI access, but no repository files, tests, or entry points. Start by reviewing the existing StackSet stack-instance views and API/CLI surfaces; done means each instance's latest overridden parameters are centrally viewable and available for automation.

Written by the indexing model from the issue text.