Search in collection should match anywhere in the item name

Right now if you're in the "browse collection" view (ex: https://debusine.debian.net/debian/base/collection/debian:environments/debian/search/) and if you type something in the name field, it will only return items whose name starts with the string that you input.

However, given that the name is often a set of fields (separated by ":" or "_"), it would be more interesting for the search to match anywhere inside the name.

For instance this search should return all armel-based images and tarballs, but it's empty. If you use "tarball:bookworm:armel", it will not be empty.