Use GraphBuilder in reorder unit tests. (#11103)

Summary:
Pull Request resolved: #11103

Use GraphBuilder in reorder unit tests.

Reviewed By: zonglinpeng

Differential Revision: D75257222

Author: eigen-k

backends/cadence/aot/TARGETS

@@ -388,6 +388,7 @@ python_unittest(
         "//caffe2:torch",
         "//executorch/backends/cadence/aot:compiler",
         "//executorch/backends/cadence/aot:fuse_ops",
+        "//executorch/backends/cadence/aot:graph_builder",
         "//executorch/backends/cadence/aot:ops_registrations",
         "//executorch/backends/cadence/aot:pass_utils",
         "//executorch/backends/cadence/aot:reorder_ops",

backends/cadence/aot/pass_utils.py

@@ -144,6 +144,19 @@ def nodes_not_connected_in_gm(
     return True
 
 
+# Returns the position of the first entry of a node of a given kind in the graph.
+def get_node_pos(
+    graph_module: torch.fx.GraphModule,
+    target: torch.fx.Node,
+) -> int:
+    pos = 0
+    for node in graph_module.graph.nodes:
+        if node.target == target:
+            return pos
+        pos += 1
+    return -1
+
+
 # Returns true if there is no instance of a node with target succ_target
 # positioned immediately after a node with target pred_target in the graph
 def nodes_not_adjacent_in_gm(