Summary

Following the work in #9392, we want the Actions column to remain visible at all horizontal scroll positions, so action buttons are easily accessible across all viewport sizes.

This issue is part of the ongoing tables sweep initiative.

Acceptance criteria

• The Actions column should be set to position: sticky and be positioned to the right of the table
• A border should be added that separates the "floating" column from other columns. It should use the same border color and width as the other table borders
• This functionality should be controlled via the new sticky?: boolean (defaults to true) property of EuiTableActionsColumnType. In the future, we may want to add the same sticky functionality to other columns.