Ability to set "ok interval"

[timsuchanek]

As of now, we can CI failures, as soon as we wrote some code that just adds 0.1kB. It would be great to set a higher granularity. A few possible options:

1. Being able to set granularity to kB
2. Being able to set a "max higher" amount, which will end up in warnings

The reason we don't just increase the kB, is that it then says, that our bundle shrank, which is also not true.

[mcataford]

Hi @timsuchanek!

I jotted down some best practices that might help your use case, especially around setting the threshold!

Let me know what you think.

I'm currently planning out work to rejig Packwatch to add in more customization, if you have any suggestions re:what would be useful in your workflow, please let me know!