feat: Add skeleton for api key module (#6451)

Adds a module skeleton for the API Key module.
Implementation of functionalities will follow in separate PRs

packages/api-key/src/joiner-config.ts

@@ -0,0 +1,25 @@
+import { Modules } from "@medusajs/modules-sdk"
+import { ModuleJoinerConfig } from "@medusajs/types"
+import { MapToConfig } from "@medusajs/utils"
+
+// TODO manage the config
+
+export const LinkableKeys: Record<string, string> = {}
+
+const entityLinkableKeysMap: MapToConfig = {}
+Object.entries(LinkableKeys).forEach(([key, value]) => {
+  entityLinkableKeysMap[value] ??= []
+  entityLinkableKeysMap[value].push({
+    mapTo: key,
+    valueFrom: key.split("_").pop()!,
+  })
+})
+
+export const entityNameToLinkableKeysMap: MapToConfig = entityLinkableKeysMap
+
+export const joinerConfig: ModuleJoinerConfig = {
+  serviceName: Modules.API_KEY,
+  primaryKeys: ["id"],
+  linkableKeys: LinkableKeys,
+  alias: [],
+} as ModuleJoinerConfig