Consider merging policy and logging into main assembly

[iancooper]

The problem with the separation of policy and logging is that most of our examples show Darker being used successfully with logging and policy attributes, but because these are not brought into scope unless we add these packages separately it can be confusing to the new user how to achieve the basic scenario.

Packaging principles would say that things that 'the unit of re-use is the unit of release', and 'keep things that change together, together'. I don't see real advantage or likelihood of these packages being released on a different schedule, so separate packages actually make this harder.

Brighter uses a single package for all these requirements, so the difference is a little confusing.

In addition ASP.NET Core has moved away from this kind of 'fine grained' package model as well.