propagate options changes to consumer

[thompsongl]

Summary

Previously, EuiSelectableList was directly modifying its props object by mutating the options list. These changes will have EuiSelectableList and EuiSelectable propagate a new, modified copy of the options up to the 'source of truth' parent.

• onChange prop now takes the options list directly as its argument
• The concept of an exposed selectedOptions list no longer exists^*. It didn't really exist to start, but this removes a misnomer reference in the examples.

^* This is different than how EuiComboBox works, which may be ok, but probably worth discussing. We can also decide this later during the abstraction work we're planning.

[cchaos]

This is different than how EuiComboBox works, which may be ok, but probably worth discussing. We can also decide this later during the abstraction work we're planning.

I'll agree. We'll figure out the EuiComboBox later, even if it means adding some things back in later.

Thanks!