Allow compact select like in the theme editor

[bakura10]

Summary

In the theme editor, Shopify added a way to show select fields with a more compact way when there is enough space to fit them inline:

It would be very great if <Select> in Polaris could offer a new showCondensed property and would automatically show select choices in the same way (or fallback to standard select when there is not enough space).

Rationale

Allow for app developers to create a more consistent experience with Shopify patterns.