Integrate site usage & site type select lists

In sms-cv!82 (merged) we added site usages & site types to the CV. In backend!436 (merged) we added the site usage fields to the backend (site type was already added earlier).

Now we want to integrate it in the SMS frontend:

• select list with autocompletion for site usage in new & edit pages (analog to compartments & sampling media for measured quantities)
• select list with autocompletion for site type (prefiltered by site usage) in new & edit pages
• post & patch requests to backend handle site type & site usage properly
• dialog to add new site usages in cv
• dialog to add new site types in cv
• extended search by site usage & site usage moved to #385 (closed)