Feature: auto-add

[dennissivia]

I suggest adding a command to automatically add changed files (that don't match any existing rule) to the given owner. This would allow a contributor to assign all the changes to a given team.

Purpose

Instead of manual changes, the author would be able to just assign all changed files to a given team.

Syntax

This is just a suggestion to have a concrete examples, I would be happy to discuss better options

codeowners-checker --auto-add @mycomp/team1

Semantics

The checker will automatically find all files, create the smallest amount of patterns (optional)
and add these rules to the codeowners file. Since inferring the most effective pattern seems hard, we could also start with simple approaches and automatically open an editor or something like that.