Block styles: Account for style block nodes that have no name

[glendaviesnz]

What?

Adds processing of block style nodes with no name to wp_add_global_styles_for_blocks.

Why?

Since #41160 was merged style block nodes with no name, eg. block element styles from theme.json, are not getting inline styles added in the frontend.
Fixes: #41443

How?

Processes nodes that have no name, but have a path.

To test

• In a block based theme add the following to theme.json styles.blocks section

			"core/columns": {
				"elements": {
					"h2": {
						"color": {
							"text": "red",
							"background": "black"
						},
						"typography": {
							"fontSize": "var(--wp--preset--font-size--small)"
						}
					}
				}
			}

• Add a columns block and within it nest an h2 header, and see if it displays with black background and red text in editor and frontend.

Screenshots, screen recording, code snippet

Before #41160 :

After:

[glendaviesnz]

@scruffian we are not sure if this is a good approach to solving this or not, you might have some better ideas based on your previous work on it.

[scruffian]

Thanks for taking care of this.

[priethor]

Cherry-picked commit c0e618a5947c7ff1a1e88d7ab6d9e0749ce31771 to the 13.4 branch. ✅

[priethor]

This PR has been included in Gutenberg 13.4-rc2.