Usability: Investigate and prototype VS piloting

### Context

As part of https://github.com/dotnet/msbuild/issues/10548 we want to invest into dogfooding of buildchecks.
In this issue we'd want to focus on possiblity to use VS feature flagging to pilot buildchecks among population of internal users

### Goals

* Investigate how VS feature flagging could be used to enable buildcheck opt-in/out in VS
* Prototype the VS GUI for opt-in/out
* Run a VS build of a sample repo (e.g. dotnet/msbuild? or some other from https://github.com/dotnet/msbuild/issues/10726) with buildchecks on and observe and log issues (there might be problems with evaluation and execution not happening as part of a single execution).