DMN17 — properly define type(e)

In some places the spec uses type(e) and other places type(e). These are different. The former provides a type-checking function that can validate a FEEL expression e without input data values (although some kind of scope is needed for disambiguation). The latter simply returns the datatype of the semantic domain element e. The former is more useful to implementors, but more work to specify. Essentially, all the semantic mapping tables need a new column to specify the result type given the input types, for each FEEL operator and builtin. The latter is a matter of generalizing Table 39. It must cover cases such as type([0,false]). It should be clear that type(e) as a function must return the most specific type (and there must be only 1), but informally the types also include those that are conformed to, so for example, [1,2,3] has types list<number>, list<Any>, Any.