Add option to control inheriting pre-build steps

[jonathansty]

By default pre-build steps of a dependency end up in the final project that added them as a dependency. I'm not sure if this is the intended behavior or not. This change adds:

• overriding of build step inheritance behavior by using the DependencySetting enum.
• Allow build order dependencies if the dependency is an exe. (Imagine a tool exe dependency for a pre-build step)
• Added a sample to demonstrate build steps issue

Not sure if this code can be taken seeing as the pre build step default behavior might be wrong anyways. This is the fix I came up with which might drive a more complete fix.