Customize value in the Metric chart

[cauemarcondes]

Is your feature request related to a problem? Please describe.
I'm using the Metrics chart to display some information to the user in the Profiling UI. I'd like to customize the value of one of the items shown, adding an icon on the right side of the value and applying a specific colour.

Describe the solution you'd like
As discussed internally adding two new properties to the MetricDatum type to specify an icon and another to specify the color of the text and icon.

Describe alternatives you've considered
An alternative solution would be change the value type from string to string | ReactElement.

Additional context

Kibana Cross Issues
https://github.com/elastic/prodfiler/issues/3510