Feat: Readonly state for uui-color-picker

[bjarnef]

Description

This PR adds a readonly state for the uui-color-picker component. It will ensure that each sub component can't be selected.
Fixes #898

Since uui-button (and button element in general) doesn't have a readonly mode, I think it makes most sense to select eyedropper button to disabled - alternative return in event, but may be odd nothing happens clicking the button.
I think it is fine the toggle button is active to switch between color format.

Depends on review of #932

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Chore (minor updates related to the tooling or maintenance of the repository, does not impact compiled assets)

Motivation and context

How to test?

Screenshots (if appropriate)

Checklist

• If my change requires a change to the documentation, I have updated the documentation in this pull request.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[github-actions]

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud