Measures inside structured types (ROW, ARRAY, MAP)

Decide whether it is valid for measures to occur inside structured types (ROW, ARRAY, MAP). If invalid, throw a validation error; if valid, change the planner to make such queries work.

A measure can occur within a ROW (struct) type because measures are part of a table's row type. It is more difficult to see measures in arrays or maps, because they would have to be treated as values (similar to lambdas) and could not be expanded at compile time.

Note that SqlTypeUtil.fromMeasure only handles struct types currently.