io/key: [API] add InputHintOp for specifying the input hint for a tag

We're about to replace key.InputOp with a filter; this change separates
the input hint into its own operation.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

internal/ops/ops.go

@@ -64,6 +64,7 @@ const (
 	TypePopPass
 	TypeInput
 	TypeKeyInput
+	TypeKeyInputHint
 	TypeSave
 	TypeLoad
 	TypeAux
@@ -139,7 +140,8 @@ const (
 	TypePassLen             = 1
 	TypePopPassLen          = 1
 	TypeInputLen            = 1
-	TypeKeyInputLen         = 1 + 1
+	TypeKeyInputLen         = 1
+	TypeKeyInputHintLen     = 1 + 1
 	TypeSaveLen             = 1 + 4
 	TypeLoadLen             = 1 + 4
 	TypeAuxLen              = 1
@@ -414,6 +416,7 @@ var opProps = [0x100]opProp{
 	TypePopPass:          {Size: TypePopPassLen, NumRefs: 0},
 	TypeInput:            {Size: TypeInputLen, NumRefs: 1},
 	TypeKeyInput:         {Size: TypeKeyInputLen, NumRefs: 2},
+	TypeKeyInputHint:     {Size: TypeKeyInputHintLen, NumRefs: 1},
 	TypeSave:             {Size: TypeSaveLen, NumRefs: 0},
 	TypeLoad:             {Size: TypeLoadLen, NumRefs: 0},
 	TypeAux:              {Size: TypeAuxLen, NumRefs: 0},
@@ -477,6 +480,8 @@ func (t OpType) String() string {
 		return "Input"
 	case TypeKeyInput:
 		return "KeyInput"
+	case TypeKeyInputHint:
+		return "KeyInputHint"
 	case TypeSave:
 		return "Save"
 	case TypeLoad: