feat: whatif input provider

[roleyfoley]

Description

AWS implementation of hamlet-io/engine#1538

Motivation and Context

Adds AWS support for the whatif provider which combines the mock and composite provider behaviour to work on existing CMDBs

How Has This Been Tested?

Tested locally

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves the structure or operation of the implementation)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Followup Actions

• Requires feat: whatif input provider engine#1538

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.
• None of the above.

[RossMurr4y]

Good to merge once hamlet-io/engine#1538 has been merged into master/main.