Property appendTo in menus

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[ ] bug report
[X ] feature request
[ ] support request => Please do not submit support request here, instead see https://forum.primefaces.org/viewforum.php?f=57

Current behavior
Getting popup menus out of the screen when they are at the right side of the page and with a panel displayed at the left.

Expected behavior
Display the popup menu positioned inside the page and not out of it.

Minimal reproduction of the problem with instructions
As in primeng, the menus should have an appendTo property to avoid being displayed out of the page.

I know this is being added in the different components as in primeng, but as I had to change it for my project, I add a PR with my changes if you want to consider them.

Thanks and greetings.