- entirely replaced by new `getIconAffordanceStyles` util, and CSS variables

+ remove unused euiButtonEmpty styles?? literally not sure what this is doing, button empty does not have borders. probably left over from old theme

+ reorder imports

- prefer using variables over mixins which contain unnecessary CSS

- most of the underlying inputs should already be setting their own styles without this component needing to (tested on all components)

- the background color also doesn't need to be set, that's specific to group styles anyway

- I removed the input border color change on readOnly as it doesn't match the default inputs - the border/box-shadow color stays the same for those, so I wanted that here as well

- border/background

+ extend `euiFormControlDefaultShadow` to allow passing only the box-shadow border and not the background gradient

- remove need for compressed/uncompressed CSS by just using `inherit`

- prefer setting a border radius + overflow hidden on the `childrenWrapper` instead of trying to set border radiuses on every possible child

- [opinionated change] Add a `<div>` append/prepend wrapper instead of using `React.cloneElement` - less fragile and a better pattern

- use `:not:has` CSS to set padding on the wrapper instead of directly on child elements

- set heights on buttons and text more explicitly

- update form variables to be more specific and remove the unused border var

+ remove extra unnecessary border-radius logic in EuiComboBox - now already handled by EuiFormControlLayout

- works correctly in browser but causes test failures

- `:has()` support is apparently flaky, so we need to pin/revert the resolution

- several props (the ones destructured and re-spread to `<EuiFieldText />`) were not correctly updating the actual control

- note: this was already broken in prod

This reverts commit d92e40d.