add notifyUsers for release promote

[nvanthao]

Summary

• Adds optional notifyUsers boolean parameter to promoteRelease and the internal promoteReleaseByAppId functions
• When provided, notifyUsers is included in the promote request payload

Test plan

• Existing promoteReleaseByAppId test passes (backward compatible — notifyUsers is optional)
• Verify callers can pass notifyUsers: true or notifyUsers: false to trigger user notifications on promote