Parallelism and Rate Limit for Workflow And QStash

Flow-Control is a newly introduced feature designed to manage rate and parallelism limits for QStash and Workflow, addressing user feedback about existing limitations in Workflow's lack of built-in controls and the per-plan constraints of Queue Parallelism. This feature enables users to define rate limits, which control the number of calls per second, and parallelism limits, which manage concurrent executions, thereby allowing configurations tailored to application needs without plan-related restrictions. Flow-Control improves upon the Queue system by eliminating the blocking issues caused by single failed messages in FIFO processing, allowing for more efficient rate-limiting and concurrency management. While Queues remain available for strict FIFO requirements, Flow-Control provides a more flexible and resilient solution, and users are encouraged to transition to this new system for better performance and scalability.