[Python] Add regression check for OpOperand owner having wrong type (#9139)

Add an integration test to ensure the `owner` property of `OpOperand`
returns a concrete op subclass, not a plain old `OpView`.

Author: fabianschuiki

integration_test/Bindings/Python/users.py

@@ -0,0 +1,23 @@
+# REQUIRES: bindings_python
+# RUN: %PYTHON% %s
+
+import circt
+from circt import ir
+from circt.dialects import arith
+
+# Ensure that the `OpOperand`s returned as the `uses` list of a value have a
+# concrete subclass of `OpView`, not just `OpView` itself. This was a regression
+# that happened upstream, where you could no longer use
+# `isinstance(use.owner, AddIOp)` to check whether a user of a value is a
+# specific op.
+with ir.Context() as ctx, ir.Location.unknown() as loc:
+  circt.register_dialects(ctx)
+  module = ir.Module.parse("""
+    %0 = arith.constant 0 : i8
+    %1 = arith.addi %0, %0 : i8
+  """)
+  zero, add = list(module.body)
+  use = list(zero.result.uses)[0]
+  assert use.owner == add
+  assert isinstance(add, arith.AddIOp)
+  assert isinstance(use.owner, arith.AddIOp)