Replace obsolete QPixmap::grabWindow() with QScreen::grabWindow()

[vineet131]

Referring to the document below and based on the warnings I am getting at runtime, we replace QPixmap with QScreen:
https://doc.qt.io/qt-5/qpixmap-obsolete.html

Description

Referring to the document below and based on the warnings I am getting at runtime, we replace QPixmap with QScreen:
https://doc.qt.io/qt-5/qpixmap-obsolete.html

Checklist

• If you are addressing rendering issues, please provide:
  • Images of both, broken and fixed renderings.
  • Source code to reproduce the issue, e.g. a YAML or rosbag file with a MarkerArray msg.
• If you are changing GUI, please include screenshots showing how things looked before and after.
  (Unfortunately I am running this on Ubuntu 22.04 right now, and not my work PC where I was getting the error, and cannot compile ROS1 code here. How do I proceed?)
• Choose the proper target branch: latest release branch, for non-ABI-breaking changes, future release branch otherwise.
  Due to the lack of active maintainers, we cannot provide support for older release branches anymore.
• Did you change how RViz works? Added new functionality? Do not forget to update the tutorials and/or documentation on the ROS wiki
• While waiting for someone to review your request, please consider reviewing another open pull request to support the maintainers of RViz. Refer to the RViz Wiki for reviewing guidelines.

[rhaschke]

Thanks for pointing out this deprecation in newer versions of Qt5. Unfortunately, this PR didn't even compile as is.

[vineet131]

Thanks for pointing out this deprecation in newer versions of Qt5. Unfortunately, this PR didn't even compile as is.

Thanks for the fixup. I couldn't compile it at home since I am not running ROS1 at home.