NuGet packages: separate instrumentation packages for fine tuning deployment

[pjanotti]

Application usage of the current NuGet package causes the deployment of all instrumentation-required packages with the application. As we grow the number of instrumentations this will get more visible. See the initial conversation here.

The proposed change is to separate the instrumentation packages and allow users concerned about deployment size to explicitly select the instrumentations that they are interested in.

Tangentially related to #1482.

[pjanotti]

The mechanism and the larger offending packages were dealt with via #2554 - I'm going to close this issue and track separately any other instrumentation package that shouldn't be installed by default with the NuGet package.