Add an IsManagedAssembly() implementation that doesn't throw on native assemblies.
Add an IsManagedAssembly() implementation that doesn't throw on native assemblies.

The downside of the previous method is that it was throwing a first-chance exception on native binaries. This makes it harder to debug.

Also the new implementation is 4 times faster for success cases and 5-6 times faster for failure cases (native binary).

mono/mono-addins,mono/mono-addins