Incosistent display of small product images in product grids

[Aljullu]

I'm opening this issue here even though it might end up requiring changes in Storefront and Core.

To Reproduce

1. Create a product with a small image (50x50 px, for example).
2. See how it looks in the Shop page, the Handpicked products block and the All Products block.
3. Notice sometimes it's scaled-up and sometimes it's not. Sometimes it's centered and sometimes it's left-aligned.

Screenshots

Storefront

Shop

All Products

Handpicked Products

TwentyTwenty

Shop

All Products

Handpicked Products

This pull in Storefront is related even though not completely fixing this: #1297.

[Aljullu]

After speaking with @LevinMedia, we decided to update all product grid blocks to render small product images as in the All Products block in Storefront, so they are scaled up to fill the space.