hotfix for lab (#9981)

Issue:
When attempting to toggle a public feature flag that didn't exist in the
workspace's feature flags array, the LabService threw a
FeatureFlagException with code FEATURE_FLAG_NOT_FOUND. This prevented
users from enabling public feature flags for the first time in their
workspace.
Fix:
Modified the LabService to handle non-existent public feature flags by
creating them instead of throwing an error. When the flag doesn't exist,
the service now saves a new feature flag record with the provided key
and value, associates it with the workspace, and returns the newly
created flag.

packages/twenty-front/src/modules/settings/lab/graphql/mutations/updateLabPublicFeatureFlag.ts

@@ -4,6 +4,10 @@ export const UPDATE_LAB_PUBLIC_FEATURE_FLAG = gql`
   mutation UpdateLabPublicFeatureFlag(
     $input: UpdateLabPublicFeatureFlagInput!
   ) {
-    updateLabPublicFeatureFlag(input: $input)
+    updateLabPublicFeatureFlag(input: $input) {
+      id
+      key
+      value
+    }
   }
 `;