Don't misreport empty-ACK writes as failed (Setting.write)

HID++ 2.0 'set' operations (SetSidetone, SetAutoSleep, SetMicGain etc.)
frequently respond with an empty ACK — just the echoed request_id with
no data bytes after. device.feature_request() strips the request_id
echo and returns the remaining payload, so our reply variable is b""
for these successful writes.

The old check `if not reply:` evaluates b"" as falsy, so we returned
None from Setting.write, which the GUI interpreted as "Read/write
operation failed" — even though the device actually succeeded.

Change the check to `if reply is None:` so empty bytes (success) pass
through and only genuine transport failures (None return from base.request)
are flagged as errors. Also add an INFO log on the real failure path so
the user can tell from the log whether a write reached the device.

This likely fixes the G522 sidetone / mic-gain / auto-sleep "Read/write
operation failed" reports — all of those features return empty ACKs for
set operations.

lib/logitech_receiver/settings.py

@@ -172,8 +172,16 @@ class Setting:
                     logger.debug("%s: prepare write(%s) => %r", self.name, value, data_bytes)
 
                 reply = self._rw.write(self._device, data_bytes)
-                if not reply:
-                    # tell whomever is calling that the write failed
+                # HID++ 2.0 "set" operations often return an empty ACK (b"").
+                # Treating empty bytes as failure (`not reply`) would misreport
+                # successful writes as errors to the GUI. Only report failure
+                # when the transport actually returned None (error or timeout).
+                if reply is None:
+                    logger.info(
+                        "%s: write on %s returned no reply (transport error/timeout)",
+                        self.name,
+                        self._device,
+                    )
                     return None
 
             return value