Missing CMake target for the debug backend layer

[stukowski]

After installation of the SDK, the CMake config module exports targets anari::anari, anari::helium, and anari::anari_test_scenes, but a corresponding target for the debug backend (anary_library_debug) seems to be missing.

A CMake target anari::anari_library_debug for the debug layer would be useful because it would allow querying the install location of anary_library_debug.dll. On the Windows platform, an application typically must copy all Anari DLLs to the application's runtime directory (where the .exe is located) so that they will be found at runtime. Having a CMake target for the debug lib would simplify this deployment step - even if the application does not link to this backend directly.

[jeffamstutz]

I just updated this in PR #165, where now all targets should be exported -- the deployment utility of targets is one I didn't think of...thanks for suggesting!