Move errors patterns and check functions to testlib

Signed-off-by: Aleksei Chetaev <alex.chetaev@gmail.com>

src/frostfs_testlib/utils/errors.py

@@ -0,0 +1,11 @@
+import re
+
+
+def error_matches_status(error: Exception, status_pattern: str) -> bool:
+    """
+    Determines whether exception matches specified status pattern.
+
+    We use re.search() to be consistent with pytest.raises.
+    """
+    match = re.search(status_pattern, str(error))
+    return match is not None