refactor Flex component

**Is your feature request related to a problem? Please describe.**
Flex and Box components are basically identical and this flexibility makes it hard to determine when to use each.

**Describe the solution you'd like**
Box should have the properties of the "box model" while Flex should have the properties of the "flex-box model".

**Additional context**
https://styled-system.com/table#flexbox

Acceptance criteria:
- Flex component should have properties for flex-box model

E: 1/2 D

Inspect the existing Flex and Box component entry points and compare their current properties with the linked styled-system flexbox table. Confirm which properties belong to each model, then verify that Flex exposes the flex-box properties described in the acceptance criteria while Box remains focused on the box model.

Written by the indexing model from the issue text.