ModelsParams record class

- Used those methods to add a `Clone` method to SafeLLamaContextHandle
 - Simplified `LLamaContext` by using the new methods
 - Sealed `LLamaContext` and `LLamaEmbedder`

- Equality, hashing etc all implemented automatically
 - Default values are defined in just one place (the properties) instead of the constructor as well
 - Added test to ensure that serialization works properly

- Deleted `NativeInfo` (internal class, not used anywhere)

The biggest single change is renaming `LLamaModel` to `LLamaContext`

The poc of the test is working know. Finally the problem error seems to be related with the process stopping.
Once I changed the context with today llama.cpp binaries is working OK