Summary:
On Windows the build artifacts cannot be easily run directly from the build
output directory without installing them.  The `$PATH` environment variable
needs to be set correctly so that the runtime library dependencies can be
found.

This updates the builder code to emit a `run.ps1` wrapper script in the build
output directory that sets `$PATH` to support running build artifacts directly
from the build directory.

Additionally, this updates the CMake-specific builder to set properly when
running the tests with `ctest`.

Reviewed By: wez

Differential Revision: D20688290

fbshipit-source-id: 5d0f4d685692bca7e37370bd88309cf7634d87f0