[EuiComboBox] Consider adding a prop to set truncation in beginning, middle, end

[1Copenut]

We've been discussing ways to communicate long label names in EuiCombobox in Kibana issue 143177. After discussion, the EUI team suggested a new prop to truncate label options at beginning, middle, or end.

This would be a way to allow virtualized option rows to accommodate longer labels, as rows must be the same height.

[github-actions]

👋 Hi there - this issue hasn't had any activity in 6 months. If the EUI team has not explicitly expressed that this is something on our roadmap, it's unlikely that we'll pick this issue up. We would sincerely appreciate a PR/community contribution if this is something that matters to you! If not, and there is no further activity on this issue for another 6 months (i.e. it's stale for over a year), the issue will be auto-closed.

[cee-chen]

This was closed by #7028