This PR renames the `h_stack` and `v_stack` to `h_flex` and `v_flex`,
respectively.
We were previously using `h_stack` and `v_stack` to match SwiftUI, but
`h_flex` and `v_flex` fit better with the web/flexbox terminology that
the rest of GPUI uses.
Additionally, we were already calling the utility functions used to
implement `h_stack` and `v_stack` by the new names.
Release Notes:
- N/A
This PR renames the `IconElement` component to just `Icon`.
This better matches the rest of our components, as `IconElement` was the
only one using this naming convention.
The `Icon` enum has been renamed to `IconName` to free up the name.
I was trying to come up with a way that would allow rendering an
`Icon::Zed` directly (and thus make the `IconElement` a hidden part of
the API), but I couldn't come up with a way to do this cleanly.
Release Notes:
- N/A
