richtext-lexical: toolbar format buttons and dropdown names are missing translations

[ciri-cuervo]

What?

The fixed and inline toolbars announce several controls in English, whatever the admin language:

• The format buttons (bold, italic, underline, strikethrough, subscript, superscript, inline code) have no label, so ToolbarButton derives their tooltip and aria-label from the feature key (inlineCode → "Inline Code").
• The insert, align, blocks and inline blocks dropdowns fall back to their group key (add, align, blocks, inlineBlocks) as aria-label whenever no item in them is active. Only the text group had a translated name.

Neither can be fixed from a project's config: a generated label is not a translation key, and a toolbar group has no label of its own.

Fixed toolbar aria-labels with the admin set to Spanish:

-["add", "blocks", "inlineBlocks", "Estilo de texto", "align", …, "Bold", "Italic", "Underline", "Strikethrough", "Subscript", "Superscript", "Inline Code", "Enlace"]
+["Insertar", "Bloques", "Bloques en línea", "Estilo de texto", "Alineación", …, "Negrita", "Cursiva", "Subrayado", "Tachado", "Subíndice", "Superíndice", "Código en línea", "Enlace"]

Why?

Screen-reader users hear "add" and "Bold" on an admin panel otherwise in their language, and sighted users see English tooltips next to translated ones (e.g. "Disminuir Sangría", "Enlace").

[ciri-cuervo]

I've already opened a PR to fix it.

• fix(richtext-lexical): translate toolbar format buttons and dropdown names #19142