The class CaseWhen has a function Else() with a return type Expression<R>, which
creates an instance of the CaseWhenElse class. According to commit history, the
CaseWhenElse class uses to also extend Expression<R>, but this was changed after a
few years to extend ExpressionWithColumnType<R> instead. Inspite of this change,
the return type of Else() did not change.

This means that the same case written as a more verbose CaseWhenElse instance
or written as a CaseWhen instance invoking Else() cannot be used interchangeably,
for example as the argument in Coalesce(), which takes ExpressionWithColumnType<*>.

Update Else() return type to be as broad as the instance it returns.

Remove extra whitespace in Case query builder.

Add unit test to ensure consistency.

Fix Detekt issues.

Remove forgotten logger.

Remove Unit return type and replace assignment operator with block body.