compiler, runtime: Refactor P4DataType to P4Type

Now that the old P4Type is a P4QualifiedType, it makes sense to
rename the data type back to just type.

Signed-off-by: Will Hawkins <hawkinsw@obs.cr>

Sources/P4Lang/Types.swift

@@ -18,10 +18,10 @@
 import Common
 
 public struct AttributedP4Type {
-  public let type: P4DataType
+  public let type: P4Type
   public let attributes: P4QualifiedType
 
-  public init(_ type: P4DataType, _ attributes: P4QualifiedType) {
+  public init(_ type: P4Type, _ attributes: P4QualifiedType) {
     self.type = type
     self.attributes = attributes
   }