test: Add the possibility to run raft tests with pytest

Closes scylladb/scylladb#22775

test/raft/README.md

@@ -0,0 +1,17 @@
+# Running tests with pytest
+
+To run test with pytest execute 
+```bash
+pytest test/raft
+```
+To execute only one file, provide the path filename
+```bash
+pytest test/raft/many_test.cc
+```
+Since it's a normal path, autocompletion works in the terminal out of the box.
+
+To provide a specific mode, use the next parameter `--mode dev`,
+if parameter isn't provided pytest tries to use `ninja mode_list` to find out the compiled modes.
+
+Parallel execution is controlled by `pytest-xdist` and the parameter `-n auto`.
+This command starts tests with the number of workers equal to CPU cores.

test/raft/conftest.py

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+#
+# Copyright (C) 2025-present ScyllaDB
+#
+# SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
+#
+from pathlib import PosixPath
+
+from pytest import Collector
+
+from test.pylib.cpp.boost.boost_facade import BoostTestFacade
+from test.pylib.cpp.common_cpp_conftest import collect_items
+
+
+def pytest_collect_file(file_path: PosixPath, parent: Collector):
+    """
+    Method triggered automatically by pytest to collect files from a directory.
+    """
+    if file_path.suffix == '.cc' and file_path.stem.endswith('test'):
+        return collect_items(file_path, parent, facade=BoostTestFacade(parent.config))
+