Additional promotion tasks

[dbason]

First some background on the types of problems we're trying to solve:
Currently we have 3 environments we in our deployment process - test, stage, prod. Test generally follows a continuous deployment pattern; everything that gets pushed to master gets built and pushed into the test environment. Kargo auto promotion works great for this, and the automatic names are fine. Docker images are built with a commit sha as their tag as we don't want to version dev/test builds. The kubernetes helm charts are just stored in the same repo as the code in a different folder; kargo freight is also great for this.

When we promote to stage we create a github release with a semantic version. This is then tested and promoted to prod. It would be great if we could do this as part of the promotion (and also update the freight alias to match). Ideally there'd be tasks to:

• updateAlias
• create/update github releases/tags

We could probably do this if we had the option to create custom promotion tasks but it seems this is a little way off. Would the suggested tasks be reasonable?