Active Storage always touches associated records when attachments are
changed. But for the Terms of Service it's important to keep the
updated_at date because that's how we find out how new it is and if a
customer accepted those terms already.
And while we migrate files, the content of the files will stay the same
and we don't want customers to be asked to accept the same terms again.
We do this for all models in the code base. There's one special case,
the ConentConfiguration which is not a model and we can't use the same
approach there. We will have to deal with that separately later.
We want to enable instance managers to upload TOS files.
I also added the rails_helper which is a new convention. It can contain
more Rails specific configuration we currently have in the spec_helper.
