Project/Component listing: New column "screenshots"

### Describe the problem

When listing projects (e.g. at translate.codeberg.org) or components I can not see if these provide screenshots for their strings. This is an important indicator of the projects quality.

### Solution brainstorm

Add a new column to the listing, name it "Screenshots" or "With screenshots". Show a % value of how many of the strings do have a screenshots attached.

### Describe alternatives you have considered

I open a project. See there are no screenshots in the first string.

### Screenshots

_No response_

### Additional context

_No response_