attributes and dimensions alignment to featuretypes-properties and grid-bands

attributes and dimensions share common aspects, such as unit/title/description min/max/avg (if numeric)

suggestion could be to merge both concepts?

Another aspect to consider in this area are featuretypes, for example the tables in a databases, or sheets in an excel (if the full database is considered a single dataset)

In stead of registering attributes directly on the content-info element, we would need to model them on a featuretype

```yaml
contentinfo:
featuretypes:
- name: books
identifier: #books
attributes:
- name: title
type: string
- name: authors
identifier: #authors
attributes:
- name: name
type: string
```

Above approach matches with what is suggested in [iso19110](https://www.iso.org/standard/57303.html)