feat: APIs for Integration Hooks (#2250)

- Introduces JSON Schema validations via JSONSchemer
- Add CRUD APIs for integration hooks

app/policies/hook_policy.rb

@@ -0,0 +1,13 @@
+class HookPolicy < ApplicationPolicy
+  def create?
+    @account_user.administrator?
+  end
+
+  def update?
+    @account_user.administrator?
+  end
+
+  def destroy?
+    @account_user.administrator?
+  end
+end