Add `tooltipContent` and `tooltipProps` support for EuiComboBox and EuiSelectable options about eui HOT 3 CLOSED

@cee-chen Do you have more context to link here?

from eui.

Original design that tooltips are intended to replace:

The tooltips replace the non-essential descriptions and will gain back valuable screen real estate.

from eui.

Scope of work:

API considerations:

• API should go on the option object/type, not on the top-level component
• It should be possible for mixed usage (i.e., some options to have tooltip content and some options to not have tooltips).
• Please start with adding the new prop to EuiComboBox first (higher priority). EuiSelectable is nice to have and will be needed for #2841, but can also wait if needed.

UX considerations:

• Triggering the tooltip on keyboard "focus" is going to require some amount of trickery/workaround as focus is technically on the search input and not on the actual list item. If this is too complicated to do, let's punt it to a separate follow-up PR and focus on mouse functionality first.
• Default tooltip delay to short and not long, please (per recent conversations with Marcialis)
• (OPTIONAL) We may want to consider automatically rendering the iInCircle icon if tooltipContent exists and has been passed, to let users know that the content exists. Would be open to thoughts on this or if we should just let users decide this themselves via the append or prepend properties

from eui.