CDK Pipelines: Use pipeline ServiceRole as default ActionRole

## Description
Multiple customers requested us to reduce the number of roles automatically created by cdk library. Since service role is applied to pipeline stage actions if no action role provided(codepipeline backend logic), we propose to add a flag in pipeline config to allow customer use pipeline service role as action role. Besides, when using CodeBuildFactory, we propose to allow customized role for CodeBuildOption in L3 construct.
Related issue:https://github.com/aws/aws-cdk/issues/27605
https://github.com/aws/aws-cdk/issues/30360
```
interface PipelineProps {
....
public readonly enablePipelineRoleForActions?: boolean; // false as default;
}

```
```
export interface CodeBuildOptions {
....
readonly role?: iam.Role;
}
```

## Roles

| Role | User
|---------------------|------------------------------
| Proposed by | @hwum
| Author(s) | @hwum
| API Bar Raiser | @
| Stakeholders | @hwum(codepipeline-dev)

> 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 proposed PipelineProps and CodeBuildOptions changes in the issue, then review related issues #27605 and #30360 and the RFC checklist. Done means the RFC advances through API approval, execution planning, and implementation completion.

Written by the indexing model from the issue text.