AWS S3Files L2 Constructs

## Description

Add L2 CDK Constructs for the AWS S3Files service.

## Roles

| Role | User
|---------------------|------------------------------
| Proposed by | @Adonca2203
| Author(s) | @Adonca2203
| API Bar Raiser | @leonmk-aws
| Stakeholders | @Pandede, @badmintoncryer

> 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`)
- [ ] 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.

Begin with the approved RFC and merged execution plan referenced by the checklist, then identify the AWS CDK package entry points and tests specified there. The issue provides no implementation files or test names, so use the plan to define the required S3Files L2 constructs and their acceptance checks. Done means the implementation is complete and the RFC checklist reaches “Implementation complete.”

Written by the indexing model from the issue text.