Entire default config for fabricator-assemble should be included the task config

Currently, the `assemble` task doesn't specify much of a configuration to pass along to `fabricator-assemble`. It relies on the implied default values. We should explicitly include all of the defaults for reference, so that the Fabricator docs aren't required to lookup the configuration keys.

Start by locating the assemble task and reviewing how it passes configuration to fabricator-assemble. Compare that configuration with fabricator-assemble's documented defaults, then explicitly include every default in the task config and verify the generated configuration remains valid.

Written by the indexing model from the issue text.