Fallback doesn’t work for fontsource fonts

[flying-sheep]

When using fontsource, no file path is passed, even though the font is available via package:

unplugin-fonts/src/loaders/fallback.ts

Lines 77 to 80 in a026c9f

	yield {
	familyName: family.name.replace(VARIABLE_SUFFIX_RE, ''),
	config: family.fallback,
	}

The lookup by family name fails if the font isn’t a classic system font or google font.