Add Chisel manifest to Ubuntu Chiseled images

[lbussell]

This is a follow-up to #5973.

The Chisel Manifest is eventually supposed to be the main way to scan Chisel images for CVEs.

We must continue using chisel-wrapper to generate dpkg cache files until the Chisel manifest is widely supported by scanning tools.

Since existing images already have a dpkg cache file, and Chisel manifests aren't widely supported yet, we should only add the Chisel manifest to new images (.NET 10+).