Allow release creation/update without specifying tickets

[fkrauthan]

Currently you have to specify at least one Jira Ticket to be able to create/update a release. However I would like to implement the following use-case:

1. Create a draft release (with list of tickets)
2. Use this action to just mark the release from draft to released (without having to detect the tickets again)

For that it would be great to be able to invoke it with a project key as an optional setting.