Problem description: 
There is no option for Screens which has the ratios 16:9 and 16:10

Steps to reproduce:
1. Open a presentation and o to the Page format settings by Format - Page
2. Tr to adjust the page size to fit the wide-screen monitors

Current behavior:
There is no easy way to set the screen size to fit widescreens

Expected behavior:

To have Screen 16:9 and 16:10

**
In fact this screen options are existing in translations in Pootle(https://translations.documentfoundation.org/tr/libo_ui/translate.html?unit=21411851 adn following string) 

But there is no option in the a/m dialog. It has only Screen.

Btw, the Impress user guide states:

---
The default Screen page is optimized for a 4:3 display (28cm x 21cm) so it is not suitable for modern wide-screen displays. You can change the slide size at any time
switching to Normal view and selecting Format > Page.
---

But however, this adjusment is done manually, by entering the size(p177).

End users may not understand this values, it will be best to have the Screen 16:9(wide) and Screen 16:10(wide) options in Impress(and in wizard) and other components.

Regards,