Support monorepos

[kettanaito]

I don't have monorepo support on the roadmap at the moment as I'm not working with monorepos in open-source. I'm leaving this discussion open to be clear that I'm not against such support and would welcome contributions that make it happen. It's also a good idea to discuss how you see the monorepo support working in this thread before jumping into implementation.

[kettanaito]

I'd love some help with this. If you've worked with monorepo release automation tools and know some insights as to how they work, please share them below. I have only a general understanding but it's not enough to move this into an actual feature.

[kettanaito]

Since Release now supports profiles (#59), we can use different profiles for different packages in the monorepo. One thing remaining is to support something like path so the next version is generated only from the commits concerning the provided path (the package path in the monorepo).