Upgrade WebC component to work with WebC v0.12

[zachleat]

Breaking changes in webc:type="render" in WebC v0.12.0: https://github.com/11ty/webc/releases/tag/v0.12.0-beta.1

[zachleat]

Folks can create their own Syntax Highlighter WebC component that is WebC v0.12.0+ friendly with the following component code:

<script webc:type="render" webc:is="template" webc:raw webc:nokeep>
export default function({slots, helpers, language}) {
	if(typeof helpers?.highlight !== "function") {
		throw new Error("[11ty/eleventy-plugin-syntaxhighlight] Missing the `highlight` helper! Did you run addPlugin on the syntax highlighter in your Eleventy config file?");
	}

	return helpers.highlight(language, slots.text.default);
}
</script>