[maps] allow users to select/deselect and re-order aggregation metric field in tooltips

[nreese]

All metric fields are automatically displayed in tooltips. Users cannot de-select a field or re-order the metric fields in the tooltip. In the screen shot below, notice how there is no tooltip configuration in the editor.

Contrast this to documents layers. In documents layers, users can select/deselect any field for tooltip and re-order them. In the screen shot below, notice how only fields in tooltip section are displayed in tooltip and user can select which fields to display and specify the display order.

Metric fields should allow this type of customization and allow users to specify whether the metric is displayed in the tooltip and allow users to re-order metrics.

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[ThomThomson]

Closing this and adding it to the maps icebox