exclude list of daffodil versions for multi-version builds

Rather than specifying the versions you want, one should exclude the versions you don't want. Then it could always attempt to create versions for every daffodil version that is not intentionally excluded, with some reasonable default that excludes Daffodil prior to say 3.7.0.

Unless a daffodil version needs to be excluded, I think we'd like to not have to update build.sbt files at all when new Daffodil versions are published.

Start by examining the build.sbt files and how they currently specify Daffodil versions for multi-version builds. Trace where the plugin discovers or creates versions, then define the intended default exclusion for versions before 3.7.0. Done means new Daffodil versions are attempted automatically unless intentionally excluded, without routine build.sbt updates.

Written by the indexing model from the issue text.