Add "expertise_level" to the MD fields

Name: Expertise Level; the field should be General Text, only occur once - i.e., not multi-valued, and required. Will be associated with other Educational Information.

Start by locating the MD field definitions in the static UI content; the issue does not name a file or test. Add the Expertise Level field as General Text, required, single-valued, and associated with Educational Information, then verify that the field appears with those properties.

Written by the indexing model from the issue text.