classes/create-spdx: extend DocumentRef to include name

This will create a more uniq DocumentRef, which will allow
the individual spdx files to be merged into a single SBOM
file reflecting the image. Do the same with the runtime dependencies
also

Signed-off-by: Saul Wold <saul.wold@windriver.com>
Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>