feat(medusa): Add feature flags to store response (#1819)

**What**
- Add `feature_flags` string array to store response

**Why**
- to provide conditional ui in admin corresponding to enabled features

Co-authored-by: Oliver Windall Juhl <59018053+olivermrbl@users.noreply.github.com>

.changeset/brave-knives-study.md

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+---
+"@medusajs/medusa": patch
+---
+
+Add feature flags to store response