test: add missing assert_equal imports

The later scripted diff only rewrites call sites.
Add `assert_equal` imports in the remaining files that still need them so the mechanical replacement can apply cleanly.

test/functional/test_framework/crypto/ellswift.py

@@ -13,6 +13,7 @@ import random
 import unittest
 
 from test_framework.crypto.secp256k1 import FE, G, GE
+from test_framework.util import assert_equal
 
 # Precomputed constant square root of -3 (mod p).
 MINUS_3_SQRT = FE(-3).sqrt()