EuiSelect no longer focuses the select when clicking on the caret

[cchaos]

By wrapping the caret svg in another wrapper, that wrapper will now accept pointer-events and so it's will no longer focus the select element. However, we can't just add pointer-events: none to the wrapper because then the buttons will stop being selectable.

cc @cjcenizal Because this broke when the EuiFormControlLayout stuff changed.

I'm also assigning an engineer, because all that logic is super complicated to me and may need further thought.