Benchmark: Compositor support

Extend the existing benchmark framework to support the compositor.
Files are added separately.

Example output:
```
$ ./benchmark.py run comp
                                         4.5                  main
ghosts                                   1.2055s              1.0243s
ghosts                                   1.4936s              1.0454s
ghosts                                   0.4414s              0.4330s

file:///Users/habib/blender-git/benchmark/comp/results.html
```

Pull Request: https://projects.blender.org/blender/blender/pulls/136600

tests/performance/tests/compositor.py

@@ -0,0 +1,63 @@
+# SPDX-FileCopyrightText: 2025 Blender Authors
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import api
+
+
+def _run(args):
+    import bpy
+    import time
+
+    device_type, _ = (args['device_type'].split("-") + [""])[:2]
+    scene = bpy.context.scene
+    scene.render.compositor_device = ('CPU' if device_type == 'CPU' else 'GPU')
+
+    test_time_start = time.time()
+    measured_times = []
+
+    min_measurements = 5
+    max_measurements = 100
+    timeout = 10
+
+    while True:
+        start_time = time.time()
+        bpy.ops.render.render()
+        elapsed_time = time.time() - start_time
+        measured_times.append(elapsed_time)
+
+        if len(measured_times) >= min_measurements and test_time_start + timeout < time.time():
+            break
+        if len(measured_times) >= max_measurements:
+            break
+
+    average_time = sum(measured_times) / len(measured_times)
+    result = {'time': average_time}
+    return result
+
+
+class CompositorTest(api.Test):
+    def __init__(self, filepath):
+        self.filepath = filepath
+
+    def name(self):
+        return self.filepath.stem
+
+    def category(self):
+        return "compositor"
+
+    def use_device(self):
+        return True
+
+    def run(self, env, device_id):
+        tokens = device_id.split('_')
+        device_type = tokens[0]
+        args = {'device_type': device_type}
+
+        result, _ = env.run_in_blender(_run, args, [self.filepath])
+        return result
+
+
+def generate(env):
+    filepaths = env.find_blend_files('compositor/*')
+    return [CompositorTest(filepath) for filepath in filepaths]