L2 Construct for AIOps

## Description

Create L2 constructs for AIOps [[Code](https://github.com/aws/aws-cdk/tree/main/packages/aws-cdk-lib/aws-aiops)].

Short description of the proposed feature:
* Investigation Group creation, which is place holder for all the investigations customer would like create under it.
* Wrap up all the related resources creation for investigation group.

## Roles

| Role | User
|---------------------|------------------------------
| Proposed by | @amandaleeatwork
| Author(s) | @amandaleeatwork
| API Bar Raiser | @alias
| Stakeholders | @amandaleeatwork

> 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`)
- [ ] Execution plan submitted (label: `status/planning`)
- [ ] Plan approved and merged (label: `status/implementing`)
- [ ] 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 linked packages/aws-cdk-lib/aws-aiops directory and the RFC workflow in this issue. Define the execution plan and implementation scope for Investigation Group and related resources; done means the constructs are implemented and the checklist reaches implementation complete.

Written by the indexing model from the issue text.