feat(medusa, utils): Allow object feature flags (#4701)

Feature flags can be set as follows:

**Environment variables**
```
MEDUSA_FF_ANALYTICS=true
MEDUSA_FF_WORKFLOWS=createProducts,addShippingMethods
```

**Project config**
```
{
  featureFlags: {
    analytics: true,
    workflows: {
      createProducts: true,
      addShippingMethods: true,
    }
  }
}
```

packages/utils/src/feature-flags/workflows.ts

@@ -0,0 +1,8 @@
+import { FeatureFlagTypes } from "@medusajs/types"
+
+export const WorkflowsFeatureFlag: FeatureFlagTypes.FlagSettings = {
+  key: "workflows",
+  default_val: false,
+  env_key: "MEDUSA_FF_WORKFLOWS",
+  description: "[WIP] Enable workflows",
+}