Support custom Well-known types

[Dogacel]

This feature contains two parts:

• Provide popular well-known Kotlin types to substitute well-known protobuf types in generated code such as Timestamp to kotlinx.datetime.Instant, Duration to kotlin.time.Duration or IntWrapper to Int?.
• [Optional] Users should be able to override certain types by the type of their choice. I.e. a user can define a convention to use UUID for certain wrapper type or a specific field.

Make sure this is defined as an option in code generator.

Make sure serialization / deserialization works with the generated types.