Add a "place" layout option

[bakura10]

After much testing and experimentation, I don't want to use the size/layout panels as they are currently implemented. They are just giving too much flexibility and introduce ton of complexity on the theme level. However, I like the simplified visuals for things like layout and I'm really curious to try the individual style input settings.

One thing I would like would be to have a "place" setting in addition to the justify and align, that would offer the 9 possible positions (top left, top center, top right, middle left, middle center, middle right, bottom left, bottom center, bottom right):

And be able to retrieve the value independently:

Setting:

{
  "type": "size.layout.placement",
  "id": "placement",
  "label": "Placement"
}

Usage:

{{ block.settings.placement.align }}
{{ block.settings.placement.justify }}

This would be handy to easily position something onto a grid:

place-self-{{ block.settings.placement.align }}-{{ block.settings.placement.justify }}