Automate module upgrade/downgrades

[tabboud]

A common theme we have seen internally is incorrectly bumping the module version when releasing a new major version of a service. There are automated tools (https://github.com/marwan-at-work/mod) available to perform the upgrade/downgrade, but we also need something that is godel aware to handle bumping the module version in the godel dist-plugin.yml, for example in the version-var field.
We could add a sub cmd to godelw mod such as godelw mod upgrade / godelw mod downgrade which wraps the module upgrade logic and also handles upgrading / downgrading the dist-plugin config.

Simple POC to show how easy it would be to wrap: master...tabboud:ta/upgrade