Deprecate PanelColor components

[chrisvanpatten]

Fixes #10367.

This PR deprecates wp.components.PanelColor and wp.editor.PanelColor in favour of wp.editor.PanelColorSettings, which is a more robust component for the reasons documented in #10367:

Overall PanelColorSettings seems superior because of its support for multiple color values and for not having the clear button float issue.

It also updates the @wordpress/editor and @wordpress/components changelogs to mention the deprecation.

One note is that deprecating wp.components.PanelColor will mean there's no component to provide a color panel that isn't wrapped inside withColorContext. Users who wish to have a panel with a color palette that uses a separate set of colors than what's defined with add_theme_support('editor-color-palette'); will need to build their own panel component.

As such, it may be desired to deprecate wp.editor.PanelColor, while keeping wp.components.PanelColor and simply fixing the visual bug noted in #10367. However, this would be a use-case that Gutenberg itself does not need/use, so it might not be worth continuing to support.

I've never done a deprecation like this… I think I got everything but would very much appreciate a close look/review 😄

[chrisvanpatten]

Need a little direction on the failing unit test. Is there a way to tell the test to expect the deprecation warning?

[jorgefilipecosta]

Hi @chrisvanpatten thank you for creating a PR with this deprecations. I agree that this component should be deprecated so we are not shipping unused code on 5.0 and we don't have multiple UI's for color picking.
Unfortanelety our new component does not completely replace what the old components offered. I will look into adding the missing functionality to the new component so we can merge this PR 👍
Thank you for your contribution.

[talldan]

Thanks for picking this up @chrisvanpatten!

I think to resolve the test failure it'll be something along the lines of adding expect( console ).toHaveWarnedWith( // ... ), as has been done here:
https://github.com/WordPress/gutenberg/blob/master/packages/block-library/src/text-columns/test/index.js#L12

[chrisvanpatten]

This should pass the failing test now, but I think is likely to miss the 4.0 milestone, so the deprecation version may need to be updated.

[chrisvanpatten]

Updated the version numbers with the assumption it can land in 4.1.

[talldan]

I think now that #10457 has been merged, this is good to go. Thanks again for picking this up @chrisvanpatten!

[chrisvanpatten]

Thanks @talldan! 🚢

[aduth]

In the context of packages, we should avoid references to WordPress-specific globals when possible (at least for changelog). Console messaging is trickier since we can't yet customize for the WordPress context, but it's a hope there we could.

See: #9753