How to evaluate a project while resolving its imports?

MSBuild has APIs to just evaluate a project's properties and items without building it (being aware of the disclaimers of #1285) but these do not take into accound any properties that are defined in any of the project's `Import`s.

I have thought of the following workaround: I will tell the `BuildManager` to build a nonexistent target, while passing `BuildRequestDataFlags.SkipNonexistentTargets` in the `BuildRequestData`.

My questions are:

1. Is there anything problematic with the approach I described? MSBuild will fully evaluate the project file and "run" a target that does not exist, ignoring it as I told. The default target will be prevented from running.

2. How about concurrency? It seems to me that the `BuildManager` class is not thread-safe. So instead of locking around its use, I have thought of creating and reusing `BuildManager` per thread. Is that good? Documentation says that "Normally there is only one build manager in a process, and it is the default build manager." but doesn't say what would happen if more than one build managers exist.