Add a "Copy to Clipboard" function to the About dialog.

The possibility to quickly copy the relevant information about the current application from an "About" dialog has become quite common. This is very useful for collecting quick and short "I used this Tool version" information bits when for example creating bug reports.

Qt Creator has a "System Information" dialog which however provides an amount of information that is perhaps too much for a quick "I used this". Reporters often paste a screenshot of the "About" dialog. So, it makes sense to have the copy feature also in the "About" dialog.

Qt Creator 12.0.0-rc1 (11.0.84)
Based on Qt 6.6.0 (MSVC 2019, x86_64)
Built on Nov 5 2023 03:48:28
From revision 18817c4088