I18N: border.radiusSizes key is missing in theme-i18n.json

[wildworks]

Originally reported at ​https://github.com/WordPress/gutenberg/issues/73688 by @twvania

For preset names to be translatable, the preset key must be defined in ​theme-i18n.json.

This is defined in ​the `theme-i18n.json` file that the Gutenberg plugin has, but not in the core one.

As a result, even if a theme developer releases a theme with radius presets, they cannot make the preset names translatable.

We need to the following keys:

{
	"settings": {
		"border": {
			"radiusSizes": [
				{
					"name": "Border radius size name"
				}
			]
		},
		"blocks": {
			"*": {
				"border": {
					"radiusSizes": [
						{
							"name": "Border radius size name"
						}
					]
				}
			}
		}
	}
}

[wildworks]

Since the radiusSizes is a new feature in 6.9, let's consider fixing it in a point release.

[hbhalodia]

Hi @wildworks, I would like to work on this. Raising the PR with a fix.

Thanks.

Trac ticket: https://core.trac.wordpress.org/ticket/64333

[wildworks]

@hbhalodia I have already submitted a PR.