scripts/qmp-shell: Add pretty attribute to HMP shell

It's less useful, but it makes the initialization methods LSP
consistent, which quiets a mypy complaint.

Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 20210607200649.1840382-19-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>

scripts/qmp/qmp-shell

@@ -322,8 +322,8 @@ class QMPShell(qmp.QEMUMonitorProtocol):
 
 
 class HMPShell(QMPShell):
-    def __init__(self, address):
-        super().__init__(address)
+    def __init__(self, address, pretty=False):
+        super().__init__(address, pretty)
         self.__cpu_index = 0
 
     def __cmd_completion(self):
@@ -421,12 +421,9 @@ def main():
     if args.qmp_server is None:
         parser.error("QMP socket or TCP address must be specified")
 
-    qemu: QMPShell
+    shell_class = HMPShell if args.hmp else QMPShell
     try:
-        if args.hmp:
-            qemu = HMPShell(args.qmp_server)
-        else:
-            qemu = QMPShell(args.qmp_server, args.pretty)
+        qemu = shell_class(args.qmp_server, args.pretty)
     except qmp.QMPBadPortError:
         parser.error(f"Bad port number: {args.qmp_server}")
         return  # pycharm doesn't know error() is noreturn