feat: added types to allow the creation of user space content services (

#7607)

* feat: added types to astro:content to allow user space content services

* Create small-apes-clap.md

---------

Co-authored-by: Nate Moore <natemoo-re@users.noreply.github.com>
Co-authored-by: Erika <3019731+Princesseuh@users.noreply.github.com>

.changeset/small-apes-clap.md

@@ -0,0 +1,5 @@
+---
+"astro": patch
+---
+
+Add `CollectionKey`, `ContentCollectionKey`, and `DataCollectionKey` exports to `astro:content`

packages/astro/content-types.template.d.ts

@@ -10,9 +10,14 @@ declare module 'astro:content' {
 
 declare module 'astro:content' {
 	export { z } from 'astro/zod';
-
-	type Flatten<T> = T extends { [K: string]: infer U } ? U : never;
-	export type CollectionEntry<C extends keyof AnyEntryMap> = Flatten<AnyEntryMap[C]>;
+
+  type Flatten<T> = T extends { [K: string]: infer U } ? U : never;
+
+	export type CollectionKey = keyof AnyEntryMap;
+	export type CollectionEntry<C extends CollectionKey> = Flatten<AnyEntryMap[C]>;
+
+	export type ContentCollectionKey = keyof ContentEntryMap;
+	export type DataCollectionKey = keyof DataEntryMap;
 
 	// This needs to be in sync with ImageMetadata
 	export type ImageFunction = () => import('astro/zod').ZodObject<{