Add design patterns for AgrO

[cmungall]

As discussed with @marieALaporte we will specify YAML DPs in the same way we are doing for TO - in particular for measurements and qualities.

At first there may be some overlap with ENVO pre-composed qualities, but we will cross that when we come to it

This encompasses #14

[KrishnaTO]

Grouping yaml patterns include:

• [x] Chemical_area_densities #123
• [ ] Processes
• [ ] Dates per terms