[Projection tooling] Lock the overall design of the projection tooling

[kotlarmilos]

Tasks

• [Projection tooling] Lay out Factory and Handler types #2855
• [Swift Projection Tooling] Apply consistent coding style across the solution #2961
• [Swift projection tooling] Bridging generic constraints for metadata retrieval #2962
• [Swift runtime features] Validate metadata pointers before saving them into cache #2966
• [Swift projection tooling] Introduce better diagnostics and error handling #2973

Note

This issue tracks progress and will be expanded with more details. If specific tasks for this issue are not clear, this means that the task is not well defined yet and needs attention.