Add support for CodePipeline

Support interacting with CodePipeline from VS Code.

For example, from #1412 :

> It's quite cumbersome when I commit some code changes to see when the deployment (in CodePipeline) is done and if it's failed what's the reason for it. I've to open the browser, go to CodePipeline and so on. It's an unnecessary context switch.
>
> I'd like to see the pipeline runs within VS Code. Ideally the runs are mapped to my git commits. The status bar should show the results of the latest run. When it's failed, a click should jump to the explorer that shows the pipeline's stages and actions and their results and logs. The explorer should also show the pipeline history.
>
> The name of the pipeline could be extracted from the cdk application. For cloudformation-based pipelines the name could be choosen manually and stored somewhere.

No files, tests, or entry points are named. Start by mapping the requested VS Code integration against the existing toolkit, then define the scope for pipeline runs, commit mapping, status-bar results, stage and action logs, history, and pipeline naming. Done should be an agreed, implementable scope for CodePipeline support.

Written by the indexing model from the issue text.