Components: move border style utils to block-editor package

[DaniGuardiola]

There are some border-related utilities marked as experimental being exported from the components package:

gutenberg/packages/components/src/index.ts

Lines 33 to 35 in d89e5a8

	hasSplitBorders as __experimentalHasSplitBorders,
	isDefinedBorder as __experimentalIsDefinedBorder,
	isEmptyBorder as __experimentalIsEmptyBorder,

Specifically:

• hasSplitBorders
• isDefinedBorder
• isEmptyBorder

This raised some alarms when making experimental components officially public, since they seem out of place, see comment: #60837 (comment)

These utilities are used in various different packages and places across the Gutenberg repo. Upon investigation, I believe a better home for them is probably the block-editor editor package. See the README: https://github.com/WordPress/gutenberg/blob/dcbccfb1ca51c560481c018a9c6f45b0ffd6aee9/packages/block-editor/README.md

This package contains a lot of style-related utilities for blocks, including the following:

• getColorClassName
• getColorObjectByAttributeValues
• getColorObjectByColorValue
• getComputedFluidTypographyValue
• getCustomValueFromPreset
• getFontSize
• getFontSizeClass
• getFontSizeObjectByValue
• getGradientSlugByValue
• getGradientValueBySlug
• getPxFromCssUnit
• getSpacingPresetCssVar
• getTypographyClassesAndStyles

cc @mirka

[mirka]

Since some of this logic is also used in the component itself, the problem with moving it to wp-block-editor is that we'd either need to duplicate the logic, or we'd be importing functions from wp-block-editor into wp-components which is a violation of the dependency direction.

I think the order of preference should be:

1. Remove (deprecate) if possible
2. Incorporate into the component API if possible
3. Move to another package

I noticed that isEmptyBorder is not used in the app anymore, so that seems like a candidate for deprecation.

For the other two, have we considered passing them as metadata to the onChange callback? Perhaps as the second argument.

[DaniGuardiola]

@mirka you're right, I hadn't realized that. Seems like I'll need to think deeper about this. Thanks for your input.