- make `css` merging as top-level prop and as iconProps work correctly

- add requiredProps to basic renders test

…n favor of array logic

…tionals & obj keys

+ DRY out repeated euiBackgroundColor() calls

…arly in props table

+ move alwayShow to top of props list

- `.euiListGroupItem-isDisabled` is no longer a className, so the :not() selector is not working and the action still appears on hover on disabled items

- passing `parentIsDisabled` as an internal prop from EuiListGroupItem and making it an array conditional solves the hover issue

- the parent li is not focusable so the `:focus &` selector doesn't work either. Changing it to to the button and `+ &` solves the issue

+ remove unnecessary comment

…array further

- the hover CSS is unnecessary if alwaysShow is true, so add a condition for it

- currently 8px on prod which generally seems to match the button padding size better

- this allows button content inside tooltips to grow to 100% of the EuiListGroupItem
- this is an enhancement from current prod behavior

- Remove unnecessary CSS on __inner - the width: 100% is totally unnecessary (tested with both extra action and without) and the word break can be applied to the __label CSS instead

- DRY out unsetting CSS by using ternary instead of base CSS (but keep empty base for naming)

- DRY out CSS by using text utils

… CSS

- use logical CSS property instead of max-width

- do not apply maxWidthDefault emotion style if using a custom inline max-width

- fix maxWidth conditional checks

- remove || fallback / type def in favor of let

- improve props documentation/typing

+ test nested `iconProps` and `extraAction` props

+ fix `extraAction` props not correctly passing/merging `className`

+ fix misc console.warn about missing EuiButtonIcon aria-label

+ add test for `style` prop on parent EuiListGroupItem, since it gets spread to the wrapped child and not the className wrapper

- they're now being correctly passed to the `EuiListGroupItemExtraAction` but they're not really doing anything / just adding a lot of noise

- consumers can simply hook into `.euiListGroupItemExtraAction` instead

- no Kibana references to these classes, so IMO they're safe to remove