The most common thing that we do with fab! is:
fab!(:thing) { Fabricate(:thing) }
This commit adds a shorthand for this which is just simply:
fab!(:thing)
i.e. If you omit the block, then, by default, you'll get a `Fabricate`d object using the fabricator of the same name.
This commit adds an /admin/customize/theme-components route,
that opens the theme page with the components tab pre-selected,
so people can navigate to that directly.
The value field of ThemeField is only used when viewing a diff in the staff action logs and local theme editing. value is being serialized into the theme index as well, which is not used. It's a huge amount of JSON that we can cut by removing it.
This also breaks up the various theme serializers into separate classes so they autoload properly (or at least restart the server on edit)
