[Maps] Customize color ramps and ranges

[alexfrancoeur]

Similar to #5058, we'd like the Maps application to allow users to customize the ranges, values and colors for a color ramp. In the first iteration, we will have these automated.

[elasticmachine]

Pinging @elastic/kibana-gis

[alexfrancoeur]

Updates from our discussion this week:

• We want to lead the charge on an EUI component here that can be utilized by all
• We'll need input from the design team, but if we're going to implement this functionality, it should be available for all types of visualizations and Canvas elements
• Static values might get interesting with zoom levels, we'll need to figure that one out. It's one of our top requests.

[arusanescu]

Can we get some direction on this request please.

[thomasneirynck]

Similar to #34478

If users can define their own color stops, they will be able to create an inverted ramp as well.

[alexfrancoeur]

@nreese 👏 👏 👏