REF: implement io.pytables._maybe_adjust_name
Besides being a well-scoped utility function, this makes it easy to use the klass constructor directly instead of `klass.create_for_block` on L3905.  Note that now we are passing `values` to the constructor instead of pinning them afterwards.  Most of what we've been doing in this file has been building up towards being able to pass things into the constructor here and avoid pinning afterward.