Use type-specific input and cell PCF elements instead of generic ones

The PCF elements Input and Cell are no longer allowed. Instead, use input and cell elements that are associated with particular value types. For example, Date Input, Text Input, Date Cell, Text Cell, and so on.

Accordingly, the new valueType property of an input or cell element is required. In most cases, valueType has a default value based on the type of element; for example, valueType for a Text Input defaults to java.lang.String. In cases where there is no default possible, such as for TypeKey Input or Range Input, you must set valueType explicitly.