[tests] Rename segwit encode and decode functions

These functions can be exported to other modules,
so be explicit that they're encoding and decoding
segwit addresses

test/functional/test_framework/address.py

@@ -8,9 +8,9 @@ import enum
 import unittest
 
 from .script import hash256, hash160, sha256, CScript, OP_0
+from .segwit_addr import encode_segwit_address
 from .util import hex_str_to_bytes
 
-from . import segwit_addr
 
 from test_framework.util import assert_equal
 
@@ -100,7 +100,7 @@ def program_to_witness(version, program, main = False):
     assert 0 <= version <= 16
     assert 2 <= len(program) <= 40
     assert version > 0 or len(program) in [20, 32]
-    return segwit_addr.encode("bc" if main else "bcrt", version, program)
+    return encode_segwit_address("bc" if main else "bcrt", version, program)
 
 def script_to_p2wsh(script, main = False):
     script = check_script(script)