Kestra 0.15.0 adds backfills from the UI, improves triggers and amplifies subflows

Kestra 0.15.0 introduces several enhancements focusing on scheduling, triggers, and subflow management, aimed at improving usability and performance. This release enables users to trigger backfills directly from the UI, allowing for more flexible and controlled management of data processing tasks. Significant updates include the introduction of an HTTP trigger feature, automatic encryption and decryption of HTTP task outputs, and a new stopAfter property for triggers, enhancing security and control over workflows. Subflows now support strongly typed outputs, simplifying data exchange between parent and subflows. The update also enhances secrets management with new encryption functions and UI features to manage logs and sensitive outputs. The UI has been revamped with a new Stats page, improved navigation, and expanded plugin support, including Azure EventHubs and Solace, to better facilitate event-driven architectures. For Enterprise Edition users, a new Setup page simplifies initial configuration, while enhanced RBAC and service account management offer more robust access controls. Overall, Kestra 0.15.0 streamlines workflow orchestration, enhances security, and expands integration capabilities.