Add a cache on /metadata (#5189)

In this PR I'm introducing a simple custom graphql-yoga plugin to create
a caching mechanism specific to our metadata.

The cache key is made of : workspace id + workspace cache version, with
this the cache is automatically invalidated each time a change is made
on the workspace metadata.

packages/twenty-server/src/engine/api/graphql/graphql-config/hooks/use-cached-metadata.ts

@@ -0,0 +1,38 @@
+import { Plugin } from 'graphql-yoga';
+
+export function useCachedMetadata(): Plugin {
+  const cache = new Map<string, any>();
+
+  const computeCacheKey = (serverContext: any) => {
+    const workspaceId = serverContext.req.workspace?.id ?? 'anonymous';
+    const cacheVersion = serverContext.req.cacheVersion ?? '0';
+
+    return `${workspaceId}:${cacheVersion}`;
+  };
+
+  return {
+    onRequest: ({ endResponse, serverContext }) => {
+      const cacheKey = computeCacheKey(serverContext);
+      const foundInCache = cache.has(cacheKey);
+
+      if (foundInCache) {
+        const cachedResponse = cache.get(cacheKey);
+
+        const earlyResponse = Response.json(cachedResponse);
+
+        return endResponse(earlyResponse);
+      }
+    },
+    onResponse: async ({ response, serverContext }) => {
+      const cacheKey = computeCacheKey(serverContext);
+
+      const foundInCache = cache.has(cacheKey);
+
+      if (!foundInCache) {
+        const responseBody = await response.json();
+
+        cache.set(cacheKey, responseBody);
+      }
+    },
+  };
+}