CardSection support image (+ fix children counting in Card) (#813)

* CardSection - support image

* Improve docs and screen

* Card - fix children filtering (for all calls)

* CardSection (image) - remove default config + add imageProps

* CardsScreen - refactor, add examples + fix some typings

* Update src/components/card/CardSection.tsx

Change testID from mainImage to image

Co-authored-by: Ethan Sharabi <[email protected]>

* Use childrens' getter

Co-authored-by: Ethan Sharabi <[email protected]>

Author: M-i-k-e-l