User, resend and cancel invite

Added the following endpoints:

• POST https://api.doit.com/iam/v1/users/\\{id}/actions/resend: Resend a pending/cancelled invite (resets 48h expiry, invalidates old link, and sends new email).
• POST /iam/v1/users/{id}/actions/cancel\: Cancels a pending invite (soft cancel; user remains visible with inviteStatus: Cancelled).

Both require usersManager permission and an Idempotency-Key header.