Clean up legacy stock config files

CHIRP-legacy used to copy the distribution stock_configs into the
user's directory, which was always messy. CHIRP-next stopped doing
that, but many users still have these files there. Instead of ignoring
distribution files if they're already in the user's directory (as was
the previous behavior), try to clean them up. If they hash to the same
value, assume they're the same and remove them.

Related to #10688

chirp/wxui/main.py

@@ -581,7 +581,7 @@ def add_stock_menu(self):
             os.makedirs(user_stock_dir, exist_ok=True)
         dist_stock_confs = sorted(
             [
-                conf.name for conf
+                (conf.name, hashlib.md5(conf.read_bytes())) for conf
                 in importlib_resources.files('chirp.stock_configs').iterdir()
                 if conf.is_file()
             ]
@@ -606,12 +606,31 @@ def add_stock(fn):
 
         stock.Append(wx.MenuItem(stock, wx.ID_SEPARATOR))
 
-        for fn in dist_stock_confs:
-            if os.path.basename(fn) not in found:
-                add_stock(fn)
-            else:
-                LOG.info('Ignoring dist stock conf %s because same name found '
-                         'in user dir', os.path.basename(fn))
+        for fn, hash in dist_stock_confs:
+            if os.path.basename(fn) in found:
+                # Remove old stock configs that were copied to the user's
+                # directory by legacy chirp.
+                try:
+                    user_fn = os.path.join(get_stock_configs(),
+                                           os.path.basename(fn))
+                    with open(user_fn, 'rb') as f:
+                        user_hash = hashlib.md5(f.read())
+                    if hash.digest() == user_hash.digest():
+                        LOG.info('Removing stale legacy stock config %s',
+                                 os.path.basename(fn))
+                        os.remove(user_fn)
+                        # Since we already added it to the user area, just
+                        # don't add it to system this time. At next startup,
+                        # it will move to the system section.
+                        continue
+                    else:
+                        raise FileExistsError('File is changed')
+                except Exception as e:
+                    LOG.info('Ignoring dist stock conf %s because same name '
+                             'found in user dir: %s',
+                             os.path.basename(fn), e)
+                    continue
+            add_stock(fn)
 
         return stock