[BETA] [EuiBasicTable/EuiInMemoryTable] Sticky action buttons columns

### Overview

`EuiBasicTable/EuiInMemoryTable sticky action buttons column` originates from a feature request: https://github.com/elastic/eui/issues/9393. It has been introduced on this PR: https://github.com/elastic/eui/pull/9430 and is currently in **beta** due to varying usage in Kibana - the sticky behavior is available only for `actions` column type, which doesn't work with EuiContextMenu usages. This issue is intended to track the progress and necessary actions to transition the functionality out of beta status and into general availability.

### Feature Description

`EuiBasicTable/EuiInMemoryTable sticky action buttons column` enables users to make the rightmost actions column visible at all times by "sticking" it on top of other columns when the table is overflowing horizontally (`scrollableInline={true}` is required).

### Next Steps

To facilitate the transition, we should:

- [ ] Analyze user feedback from beta testers
- [ ] Address any reported bugs or issues
- [ ] Update documentation for full release
- [ ] ~Define performance benchmarks (if applicable)~