Pipelining and continuous deployment support grayscale releases [blue-green, canary]

**What's it about?**
After the image is built, switch from DevOps project to project, open the grayscale release page, and enter the image name to create the blue-green deployment and canary release tasks. I don't think it's more convenient to use the grayscale publishing process this way.

Planning to integrate blue-green deployments and canary releases into continuous deployment to string together the entire release process? That is, every time the pipeline is executed, when the release step is reached, the blue-green or canary release can be selected.

**What's the reason why we need it?**
Kubesphere integrates many projects in the cloud native ecosystem, and grayscale release should be part of continuous integration. At present, the devops release process and grayscale release are not connected in series, which is very inconvenient to release.

I believe this is an important feature for Kubesphere. There're a few use cases:

* After the pipeline is packaged and mirrored, it enters the continuous deployment integration link, you can choose the release method, and pop up to create a grayscale release task until the functional test is passed, and the grayscale release task ends. complete the all processes.

Please leave your comments below if there's anyone agrees with me. Or just give me a thumb up.

**Area Suggestion**

/kind feature-request

No files, tests, or entry points are named. Start by mapping the existing DevOps release flow and grayscale-release flow, then determine how blue-green or canary selection and task status would connect them. Done means the pipeline can select a release method and carry it through testing and completion.

Written by the indexing model from the issue text.