Give Const a name

Author: acl-cqc

hugr-core/src/ops/constant.rs

@@ -33,12 +33,19 @@ pub struct Const {
     /// The [Value] of the constant.
     #[serde(rename = "v")]
     pub value: Value,
+    /// The external name of the constant for linking, if any
+    pub name: Option<String>,
 }
 
 impl Const {
-    /// Create a new [`Const`] operation.
+    /// Create a new [`Const`] operation that cannot be linked against.
     pub fn new(value: Value) -> Self {
-        Self { value }
+        Self { value, name: None }
+    }
+
+    /// Create a new [`Const`] operation available for linking
+    pub fn new_public(value: Value, name: impl ToString) -> Self {
+        Self {value, name: Some(name.to_string()) }
     }
 
     /// The inner value of the [`Const`]