LMS-1103 Add document check - SI year

Summary of feature request

Add a mandatory document check for the presence of an SI year in the number block.

Background

At the point of submission for publication, all SIs must contain a year in their number field in order to be accepted. (The Publishing system needs the year in order to know which year’s series to allocate the SI number from, and which year to put in the published metadata.)

Currently Lawmaker has a document check for poorly formed SI number fields, but if the year is left completely blank there is no error warning.