[test] Logging a list of available features before executing the tests (#7871)

Author: moiseev

test/lit.cfg

@@ -1079,3 +1079,5 @@ if config.lldb_build_root != "":
     # finishSwigPythonLLDB.py in the lldb repo
     python_lib_dir = get_python_lib(True, False, config.lldb_build_root)
     config.substitutions.append(('%lldb-python-path', python_lib_dir))
+
+lit_config.note("Available features: " + ", ".join(config.available_features))