Introduce Page.Container component

[jaridmargolin]

Right now the Page component acts a flex container, allowing to render Artboard's and SymbolMaster's in either a column or a row.

I'd like however to have unlimited flexibility rendering Pages by composing Flex components. By having some sort of arbitrary Flex container, I could layout items on a Page in complex grids if necessary.

This would require us introducing a new Component that can be utilized to compute Yoga layout, but doesn't actually result in any backed rendering.

@mathieudutour - I know this goes against some of your comments in #291, but I'm not sure how else to achieve this.

note: it doesn't need to be called Flex.

[mathieudutour]

Yes I can see the use case. Maybe we could make it super clear and have it as a component exposed on the Page component like Page.Container or something. That way we don't create a new component per se so it might be easier to understand where and how to use it.

What do you think?

[jaridmargolin]

Ahhh, yes. I like the idea of Page.Container.... I will open a PR :) Thanks for the suggestion.