Introduce Versioning to the Watcher

[ruanxin]

Description

Now watcher should be ready to release on PROD, but we still lacking of the process to alignment watcher versioning on Lifecycle manager release.

The Release Process concludes with the following:

• Only keep on branch main; no release branches
• Release always from main
• Introduce semantic versioning incl. Release notes
• No regular releases

ACs

• Introduce Prow release pipeline triggered using tags
  • You can use CLI prow pipeline as inspiration rel-kyma-cli
  • Align with team Neighbours how to tag image with semantic versioning (hint)
  • Stick with prow to build image, since this has signing mechanism
• Release notes should be created automatically using goreleaser
  • hint using similar as make target and called in pipeline

[Tomasz-Smelcerz-SAP]

I think the ACs for the goreleaser are not relevant anymore. We can't use the same process as the CLI, we have to use secured environment for building and publishing the artifacts.
Using goreleaser just to provide the changelog doesn't make much sense as there are many other ways to produce the changelog.