move hw_wallet.py from plugins to electrum library

electrum/plugins/safe_t/cmdline.py

@@ -1,6 +1,7 @@
 from electrum.plugin import hook
+from electrum.hw_wallet import CmdLineHandler
+
 from .safe_t import SafeTPlugin
-from ..hw_wallet import CmdLineHandler
 
 class Plugin(SafeTPlugin):
     handler = CmdLineHandler()