compiler, runtime: Refactor P4Type to P4QualifiedType

Also, refer to the different pieces of the qualified type as
qualifiers and not attributes.

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

Snippets/use-program-instanceswithtypes.swift

@@ -39,8 +39,8 @@ let p4_program_with_control_decl = """
 
 
 // snippet.include
-let flter = { (tipe: P4Type) -> Bool in
-  switch tipe.dataType(){
+let flter = { (tipe: P4QualifiedType) -> Bool in
+  switch tipe.baseType(){
   case let c as Control: c.name == "simple"
   default: false
   }