refactor(cli): use command runner to run predictable logic

[ematipico]

Summary

The CLI that runs the commands has become very repeated. I had attempted few refactors before, and eventually landed on this one.

As for now, this refactor only touches the format command, to show how it has become. We can discuss the architecture here, and one we merge this PR, I will refactor the rest of the commands.

We now have a CommandRunner trait that all the payloads need to implement in order to be run. Eventually, only the run command is called, then the rest is just repeated logic that was moved from format.rs.

Pros

With a trait, now the bulk of the logic lives inside one single function, and it is shared among commands. This should reduce the repeated work, especially when we add new CLI options that affect multiple commands e.g. VCS integration.

Cons

When merging the configuration, because we use &mut self, we need to use clone() every time we need to merge CLI options into the configuration loaded from disk.

Test Plan

The existing tests should pass