Moves (and renames) check_user_pk to common so cli can use it too. Fixes the regex so it only accepts {02, 03} as prefix

common/tools.py

@@ -1,10 +1,23 @@
 import re
-import os
 import logging
 from pathlib import Path
 from common.constants import LOCATOR_LEN_HEX
 
 
+def check_compressed_pk_format(compressed_pk):
+    """
+    Checks if a given value is a 33-byte hex encoded string.
+
+    Args:
+        compressed_pk(:obj:`str`): the value to be checked.
+
+    Returns:
+        :obj:`bool`: Whether or not the value matches the format.
+    """
+
+    return isinstance(compressed_pk, str) and re.match(r"^0[2-3][0-9A-Fa-f]{64}$", compressed_pk) is not None
+
+
 def check_sha256_hex_format(value):
     """
     Checks if a given value is a 32-byte hex encoded string.