Allow to manually build the package for development branches

For GitLab Runner project we have the S3 deployment for every development branch. This allows us to easily download and manually test an updated Runner before it will be merged into master. It's especially useful when users are being asked to test if the prepared change resolves a reported problem.

This MR adds a similar mechanism for Runner's Helm Chart project. For simplicity, for now it adds a manual action that stores packaged archive as an artifact. This artifact will be stored by default for 7 days.