Automate SBOM generation for container images

[jayavenkatesh19]

Towards https://github.com/rapidsai/build-infra/issues/280

Adds SBOM to base and notebook images

• Add a new stage in each Dockerfile called syft-base with the Syft binary installed on a minimal alpine 3.20 image.
• The main docker build is done using a stage called base-build and notebooks-build to differentiate it from the final image.
• Another stage is added called base-sbom/ notebooks-sbom where the built stage is mounted to a specified location on the syft-base stage
• A syft-scan is done on the mounted location, and an SBOM is generated.
• The generated SBOM is then copied to the final stage, with image name and tags kept unchanged to ensure no changes to how these images are built and published.