feat: Add limited support for objectPosition property on images

[damianstasik]

Currently any image that has objectFit property will be centered without any way to control this behavior.

This PR adds a limited support for objectPosition for images, by tweaking what is being passed to preserveAspectRatio property.

By limited I mean you need to pass both X and Y, and for both of them you can pass only three keyword values:

• for X: left, center, right
• for Y: top, center, bottom

It is still something more than always center, so I hope it is useful enough to get merged.

I am marking this as draft, because I am not sure what is the preferred way of testing it. Should I convert the test cases to use snapshots?