[#1] Add method get_private_key_from_wif

Signed-off-by: ilyas585 <niyazov2023@gmail.com>

tests/conftest.py

@@ -0,0 +1,20 @@
+import pytest
+
+from frostfs_api.crypto.key_extension import KeyExtension
+from frostfs_api.client.verifier import Verifier
+from frostfs_api.client.signer import Signer
+
+
+@pytest.fixture(scope="session")
+def client_key_extension():
+    return KeyExtension()
+
+
+@pytest.fixture(scope="session")
+def client_signer():
+    return Signer()
+
+
+@pytest.fixture(scope="session")
+def client_verifier():
+    return Verifier()