feat(py): Parametric int type helper, and arbitrary width int constan…

…ts (#1406)

- Adds an `int_tv` method to create parametric integer types
- Adds a `width` member to `IntVal`, so we can define constants for
other integer widths

hugr-py/src/hugr/std/int.py

@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from typing import TYPE_CHECKING, ClassVar
 
 from typing_extensions import Self
@@ -15,7 +15,7 @@
 
 
 def int_t(width: int) -> tys.Opaque:
-    """Create an integer type with a given log bit width.
+    """Create an integer type with a fixed log bit width.
 
 
     Args:
@@ -45,9 +45,10 @@ class IntVal(val.ExtensionValue):
     """Custom value for an integer."""
 
     v: int
+    width: int = field(default=5)
 
     def to_value(self) -> val.Extension:
-        return val.Extension("int", INT_T, self.v)
+        return val.Extension("int", int_t(self.width), self.v)
 
 
 OPS_EXTENSION: tys.ExtensionId = "arithmetic.int"