[Reddit] Ability to disable the minimal size and resolution validation for wallpapers from the corresponding subreddit

[visvital]

Story:
As a user,
I want to be able to receive the images from Reddit source without specifying the minimal size and resolution,
So that every image from the source can be considered as a valid wallpaper, and the way it fits could just rely on the wallpaper scaling mode setting.

Acceptance criteria:

1. The system provides the option to specify empty fields for minimal resolution and minimal display ratio in the Reddit source settings.
2. When the empty limitations are specified, the system assumes that any image from the corresponding source can be used as a wallpaper.