Block Supports: Add text columns (column count) to typography block supports

[ramonopoly]

Add a new block support feature to the typography toolset to allow control over CSS column count for blocks displaying multiline text.

Gutenberg PR that introduces this change in the plugin: ​https://github.com/WordPress/gutenberg/pull/33587

This allows further design possibilities.

This PR adds the PHP changes for the following Gutenberg PR:

• ​https://github.com/WordPress/gutenberg/pull/33587

Frontend changes also need to be ported and will be done before WP 6.3 beta (before June 27)

Testing:

npm run test:php -- --filter Tests_Theme_wpThemeJson

@aaronrobertshaw do these ported changes look okay to you?

Thank you for wrangling this backport @ramonjd

I think we might need to also backport the addition of textColumns support to the style engine which was added to Gutenberg in ​https://github.com/WordPress/gutenberg/pull/46566. As it's all for one feature, should that be part of this backport or separate?

The changes in this PR look good in terms of addressing ​https://github.com/WordPress/gutenberg/pull/33587 though.

I think we might need to also backport the addition of textColumns support to the style engine which was added to Gutenberg in ​https://github.com/WordPress/gutenberg/pull/46566.

Good spotting. I'll add it to this PR. 👍

thanks

[isabel_brison]

In 55985:

Editor: add text columns to typography support.

Adds a text columns feature to the typography block support that uses CSS column-count for multi-column text.

Props ramonopoly, aaronrobertshaw.
Fixes #58549.

Committed in r55985 / ​9a9a672.