Migrate const_finder_test to use package:test (#55132)

... instead of some home-grown framework.

This is the last test in the engine that uses custom command line arguments to start. As of this PR, `dart test` including full debugging in an IDE works across all Dart tooling code.

I tried to make this idiomatic as much as possible without changing the logic.

Author: matanlurey

testing/run_tests.py

@@ -988,14 +988,7 @@ def build_dart_host_test_list(build_dir):
       ),
       (os.path.join('flutter', 'tools', 'build_bucket_golden_scraper'), []),
       (os.path.join('flutter', 'tools', 'clang_tidy'), []),
-      (
-          os.path.join('flutter', 'tools', 'const_finder'),
-          [
-              os.path.join(build_dir, 'gen', 'frontend_server_aot.dart.snapshot'),
-              os.path.join(build_dir, 'flutter_patched_sdk'),
-              os.path.join(build_dir, 'dart-sdk', 'lib', 'libraries.json'),
-          ],
-      ),
+      (os.path.join('flutter', 'tools', 'const_finder'), []),
       (os.path.join('flutter', 'tools', 'dir_contents_diff'), []),
       (os.path.join('flutter', 'tools', 'engine_tool'), []),
       (os.path.join('flutter', 'tools', 'githooks'), []),

tools/const_finder/pubspec.yaml

@@ -18,4 +18,6 @@ dependencies:
 
 dev_dependencies:
   collection: any
+  engine_repo_tools: any
   path: any
+  test: any