scripts: Scan CWD in object tracker generator.
scripts: Scan CWD in object tracker generator.

This makes it more easy to locate a header in configs which have the
CWD set to something less obvious. In Chrome's case the build directory
is completely separated from the script directory.

Also reset the CWD after the header is found to keep the build intact.

This is similar to the change to the parameter validation generator.

KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools,KhronosGroup/Vulkan-Tools