{container} Bugfix Azure#15856,Azure#18251,Azure#18275: az container …

…exec - decode received bytes as utf-8 string (Azure#18384)

* decode binary string as utf-8

* updates suggested code style changes

src/azure-cli/azure/cli/command_modules/container/custom.py

@@ -682,6 +682,8 @@ def _cycle_exec_pipe(ws):
     r, _, _ = select.select([ws.sock, sys.stdin], [], [])
     if ws.sock in r:
         data = ws.recv()
+        if isinstance(data, bytes):
+            data = data.decode('utf-8')
         sys.stdout.write(data)
         sys.stdout.flush()
     if sys.stdin in r: