[BUG] Slow performance using wallpapers and zoom on python gui

[mateodurante]

Describe the bug
When you set a wallpaper and you do very close zoom in this take a long time to render it because makes image resize to large sizes and becomes non performant.

To Reproduce
Steps to reproduce the behavior:

1. Open core-gui (python)
2. Set wallpaper image (preferent a big one)
3. Use anyone of upper-left/centered/scaled
4. Do a zoom in with mouse wheel many times

Expected behavior
Can do a very close zoom with large images.

Desktop (please complete the following information):

• OS: Ubuntu 20.04
• CORE Version 8.1.0

Additional context
I tried every option and check code, I found that the problem is that code resizes images to a large sizes. So I worked on this and I made a fix for all view types (upper-left/centered/scaled and resize_to_wallpaper) and now can make very large zooms. Can I PR this to develop?