EC2 Image Builder L2 Constructs

## Description

[Amazon EC2 Image Builder](https://docs.aws.amazon.com/imagebuilder/latest/userguide/what-is-image-builder.html) is a fully managed AWS service that helps you automate the creation, management, and deployment of customized, secure, and up-to-date server images. You can use Image Builder to create Amazon Machine Images (AMIs) and container images for use across AWS Regions.

This RFC proposes L2 constructs for EC2 Image Builder, to simplify the creation of EC2 Image Builder resources in CDK.

## Roles

| Role | User
|---------------------|------------------------------
| Proposed by | @tarunb12
| Author(s) | @tarunb12
| API Bar Raiser | @kumsmrit
| Stakeholders |

> See [RFC Process](https://github.com/aws/aws-cdk-rfcs#rfc-process) for details

## Workflow

- [x] Tracking issue created (label: `status/proposed`)
- [x] API bar raiser assigned (ping us at [#aws-cdk-rfcs](https://cdk-dev.slack.com/archives/C025ZFGMUCD) if needed)
- [x] Kick off meeting
- [x] RFC pull request submitted (label: `status/review`)
- [x] Community reach out (via Slack and/or Twitter)
- [x] API signed-off (label `status/api-approved` applied to pull request)
- [x] Final comments period (label: `status/final-comments-period`)
- [x] Approved and merged (label: `status/approved`)
- [x] Execution plan submitted (label: `status/planning`)
- [x] Plan approved and merged (label: `status/implementing`)
- [x] Implementation complete (label: `status/done`)

---

> Author is responsible to progress the RFC according to this checklist, and
apply the relevant labels to this issue so that the RFC table in README gets
updated.

Start with the issue's linked Amazon EC2 Image Builder documentation and the RFC Process guidance. The issue describes a broad proposal rather than naming implementation files or tests, and its checklist marks implementation complete, so confirm the current RFC status before doing further work.

Written by the indexing model from the issue text.