Acceptance criteria:

• patched-description/label-invalid 422 error in the following endpoints - items/descriptions/ and properties/descriptions (and the same for labels)
• The error will be of the following form

{
  "code": "patched-[label/description/statement]-invalid-field"
  "message": "Patched value for '{field}' is invalid"
  "context": { "path": <field>, "value": <value>}
}

Older notes:
Similar to what was done for aliases: https://phabricator.wikimedia.org/T337371

and also decide which phrasing we'd like to keep (Statement version has: Invalid input for ... and Aliases was decided to be: Patched value for ....)
https://mattermost.wikimedia.de/swe/pl/5ss4di8pct8juqm9a9fpxgik4o