[Swift language features] Implement Swift structs in C#

[kotlarmilos]

Tasks:

• [Swift Binding] Projecting frozen structs #2797
• [SwiftBindings] Add support for non-frozen structs #2870
• [SwiftBindings] Add IndirectResult support for non-constructor methods #2885
• [SwiftBindings] Implement algorithm deciding whether a struct should be projected as class or struct #2886
• [SwiftBindings] Add support for failable constructors #2888
• [SwiftBindings] Generate fully qualified names for projected types #2889
• [SwiftBindings] Revert emitting Swift projection on error #2890

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.