feat: add defaultDateType config

quartz/components/Date.tsx

@@ -1,7 +1,16 @@
+import { GlobalConfiguration } from "../cfg"
+import { QuartzPluginData } from "../plugins/vfile"
+
 interface Props {
   date: Date
 }
 
+export type ValidDateType = keyof Required<QuartzPluginData>["dates"]
+
+export function getDate(cfg: GlobalConfiguration, data: QuartzPluginData): Date | undefined {
+  return data.dates?.[cfg.defaultDateType]
+}
+
 export function formatDate(d: Date): string {
   return d.toLocaleDateString("en-US", {
     year: "numeric",