Provide defaults for font weight/styles on FSE based on the json

[MaggieCabrera]

In the same vein as #27116 we should provide a default style for some basic tags using the values from theme.json. The editor is already providing specific values, but I believe these should come from the json when they are provided and also affect the frontend so they don't need to be declared within the theme such as these:

b,
strong {
	font-weight: var(--wp--preset--font-weight--bold);
}

dfn,
cite,
em,
i {
	font-style: var(--wp--preset--font-style--italic);
}