LinkControl: Improve the link preview and Copy link aria labels about gutenberg

[afercia]

For a new, more meaningful, aria-label for the link preview it's worth reminding the link preview can show a few things that are conceptually different.

The fetched information of an external site displayed in a 'rich data' preview, including the site icon:

Same for an internal link.

Or, if the link destination page can't be fetched, it will display a generic icon, the link text, and the link url with the protocol part stripped out:

Or, when the link text is the same as the link url, it may show only the link:

Given this UI can show different things, sometimes it may actually not be a 'preview'. A new, more meaningul, labeling should likely avoid the term 'preview' and use a more generic terminology to commuincate users this is generic information about the destination page.

[afercia]

Note: translatable should avoid concatenation. In the case illustrated below, the colon : is not translatable.
The WordPress l10n guidelines recomment to always use fully translatable strings, including punctuation.

gutenberg/packages/block-editor/src/components/link-control/link-preview.js

Lines 146 to 150 in e33cb88

	label={ sprintf(
	// Translators: %s is a placeholder for the link URL and an optional colon, (if a Link URL is present).
	__( 'Copy link%s' ), // Ends up looking like "Copy link: https://example.com".
	isEmptyURL || showIconLabels ? '' : ': ' + value.url
	) }

[afercia]

Additionally: when the preference 'Show button text labels' is enabled, all three buttons still show the tooltips, they just repeat the visible text. That's redundant and should be avoided as it's done for other buttons in the UI.

Screenshot: