refactor: move defaultDateType to CreatedModifiedDate plugin

quartz/cfg.ts

@@ -1,4 +1,3 @@
-import { ValidDateType } from "./components/Date"
 import { QuartzComponent } from "./components/types"
 import { ValidLocale } from "./i18n"
 import { PluginSpecifier } from "./plugins/loader/types"
@@ -68,8 +67,6 @@ export interface GlobalConfiguration {
   analytics: Analytics
   /** Glob patterns to not search */
   ignorePatterns: string[]
-  /** Whether to use created, modified, or published as the default type of date */
-  defaultDateType: ValidDateType
   /** Base URL to use for CNAME files, sitemaps, and RSS feeds that require an absolute URL.
    *   Quartz will avoid using this as much as possible and use relative URLs most of the time
    */