Add support for discovering tags in multi-branch pipeline

Created by: LinuxSuRen

What would you like to be added: Adding a switch to enable or disable a multi-branch pipeline to discover tags or not.

Why is this needed: In some cases, we need to trigger the multi-branch pipeline via the git tags. Kubephere already supports trigger a pipeline via PR or branches. It would be good to have this feature. I have already created a PR for the back-end part. https://github.com/kubesphere/kubesphere/pull/3125