L2 Constructs for Bedrock AgentCore Memory

## Description

L2 Constructs for Bedrock AgentCore Memory (https://docs.aws.amazon.com/bedrock-agentcore/latest/devguide/memory.html)

## Roles

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

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

## Workflow

- [x] Tracking issue created (label: `status/proposed`)
- [ ] API bar raiser assigned (ping us at [#aws-cdk-rfcs](https://cdk-dev.slack.com/archives/C025ZFGMUCD) if needed)
- [ ] Kick off meeting
- [ ] RFC pull request submitted (label: `status/review`)
- [ ] Community reach out (via Slack and/or Twitter)
- [ ] API signed-off (label `status/api-approved` applied to pull request)
- [ ] Final comments period (label: `status/final-comments-period`)
- [ ] 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 Bedrock AgentCore Memory documentation and the repository's RFC Process. This issue is only a tracking proposal, so there are no implementation files or tests named; the next concrete milestone is an RFC pull request, followed by the checklist through API approval and implementation planning.

Written by the indexing model from the issue text.