…ng statically. Fixes xamarin#10950, xamarin#11145 and xamarin#12100.

* Add support for Mono Components.

* Modify how we look up symbols from native libraries shipped with Mono: we keep
  track of which native libraries we linked with, and depending on how we linked
  to those assemblies, we look the symbols up at runtime in either the current executable
  (if linking statically), or the actual library (where the P/Invoke says they're
  supposed to be).

* This means that we have to propagate how libmono is linked from the MSBuild code
  to the Application class so that our existing logic is able to correctly determine
  which native mono lib to use.

* Modify how we list the P/Invokes we need to preserve by taking into account the
  list of native libraries from Mono we have to link with (for .NET). For legacy
  Xamarin, I've reverted the logic to how it was before we started adding .NET support.

Fixes xamarin#10950.
Fixes xamarin#11145.
Fixes xamarin#12100.