Improve error messages and fix error reporting of cases where the common super type can't be calculated

[alexanderpann]

• The goal was to make error messages more friendly, fix the spelling and make them more consistent.
• The common super type calculation itself is correct, but we still assumed that it returns null in the error case instead of a JoinType which is in many cases an indication that the calculation failed.
• For some cases, the interface ITyped is now implemented which makes the usability better because it has a cardinality of 0..1 + a checking rule. This is the main reason for the many changed files because I created automatic migrations for that. As a followup, we could also take a look at the interface IOptionallyTyped which could be implemented by many concepts.
• The PR also fixes https://github.com/IETS3/iets3.opensource/issues/1072 if I understand the ticket correctly.