compiler, runtime, common, testing: Support Directions on Parameters and Attributed Types

Add support for directions on parameters and attributed types. The
latter is necessary to support the former, but is not limited to
the direction use case. An attributed type is a P4 type with attributes
(like its direction, whether it is read only, etc.) Other attributes
will be added in the future.

Changes necessary to support attributed types include:
1. Global instances tracked during compilation are not attributed
types and not simply types.
2. (future) Type checking will have to make sure that a types
attributes do not affect type compatibility.

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

Sources/P4Compiler/Declarations.swift

@@ -108,7 +108,8 @@ extension FunctionDeclaration: CompilableDeclaration {
     // Add the parameters into scope.
     var function_scope = context.instances.enter()
     for parameter in function_parameters.parameters {
-      function_scope = function_scope.declare(identifier: parameter.name, withValue: parameter.type)
+      function_scope = function_scope.declare(
+        identifier: parameter.name, withValue: parameter.attributedType())
     }
 
     let maybe_function_body = Parser.Statement.Compile(
@@ -331,7 +332,7 @@ extension P4Lang.Parser: CompilableDeclaration {
     for parameter in parameter_list.parameters {
       current_context = current_context.update(
         newInstances: current_context.instances.declare(
-          identifier: parameter.name, withValue: parameter.type))
+          identifier: parameter.name, withValue: parameter.attributedType()))
     }
 
     currentChildIdx += 1
@@ -374,7 +375,7 @@ extension P4Lang.Parser: CompilableDeclaration {
           parser,
           context.update(
             newInstances: updated_context.instances.declare(
-              identifier: parser.name, withValue: parser))
+              identifier: parser.name, withValue: P4TypeAttributed(parser, [])))
         ))
     case Result.Error(let error): return .Error(error)
     }
@@ -436,7 +437,8 @@ extension Control: CompilableDeclaration {
     // Before continuing, make sure to put the parameters into context.
     var control_scope = local_context.instances.enter()
     for parameter in control_parameters.parameters {
-      control_scope = control_scope.declare(identifier: parameter.name, withValue: parameter.type)
+      control_scope = control_scope.declare(
+        identifier: parameter.name, withValue: parameter.attributedType())
     }
     local_context = local_context.update(newInstances: control_scope)
 
@@ -505,7 +507,7 @@ extension Control: CompilableDeclaration {
         declared_control,
         context.update(
           newInstances: context.instances.declare(
-            identifier: control_name, withValue: declared_control))
+            identifier: control_name, withValue: P4TypeAttributed(declared_control, [])))
       ))
   }
 }
@@ -566,7 +568,8 @@ extension Action: Compilable {
     // Add the parameters into scope.
     var function_scope = context.instances.enter()
     for parameter in action_parameters.parameters {
-      function_scope = function_scope.declare(identifier: parameter.name, withValue: parameter.type)
+      function_scope = function_scope.declare(
+        identifier: parameter.name, withValue: parameter.attributedType())
     }
 
     let maybe_action_body = Parser.Statement.Compile(