Formalize useColorPicker as a component export

[thompsongl]

Looks like useColorPicker is probably a service we'll want to document and export if it's this helpful in a consuming application?

Originally posted by @cchaos in #2850

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This idea extends beyond this case to other components with slightly-non-standard form element input-output expectations.

[Dilshaad21]

@thompsongl I want to work on this. Is it related to the src/docs part

[chandlerprall]

@Dilshaad21 This change is stand-alone and wouldn't interact with other changes or parts of EUI; specifically it's moving useColorPicker (and useColorStop) from src-docs/src/views/color_picker/utils.js and into a new service file in src/services Feel free to take and work on it!

I'd recommend renaming this helper to something like useColorPickerState, as we've also used hooks to return actual Components themselves and can see the naming convention overlapping. Thoughts, @thompsongl ?

[Dilshaad21]

Ok @chandlerprall, going for it

[thompsongl]

useColorPickerState is a good name. I haven't fully thought through all of the impacts this could have, but a relocation and rename seem like a good start.

[mridulgogia]

@Dilshaad21 Are you working on this?

[mridulgogia]

@thompsongl Can I work on this issue?

[thompsongl]

I've made some modifications to the function in #2850. We should wait until that PR merges before moving forward again with work on this issue

[chandlerprall]

#2850 has been merged, this is ready to be worked on @mridulgogia

[thompsongl]

Done in #3067