Offer a select for Jenkins agent labels in the Pipeline editing page

Created by: LinuxSuRen

What would you like to be added: Offer a select for Jenkins agent labels in the Pipeline editing page. Please see the following screenshot:

You can get the data from this API:

GET /kapis/devops.kubesphere.io/v1alpha2/devops/rickfzhvl/jenkins/labelsdashboard/labelsData

The response could be like:

{
   "status":"ok",
   "data":[
      {
         "label":"a",
      },
      {
         "label":"b",
      }
   ]
}

Why is this needed: Type the agent label name manually is not reliable. Firstly, users don't know which labels they can use. Secondly, people can make mistakes by typing.

/area devops

Backend: We need a new plugin label-linked-jobs-plugin. But I've not put it into ks-jenkins. I'll leave a comment below once it's ready.