grpc-native: Intial setup with minimal C++/C/Kotlin interface

[Jozott00]

Subsystem
gRPC Client Native

Problem Description
To implement the gRPC client on Kotlin/Native, we utilize the official gRPC C++ library internally. To achieve this, we need to create a C wrapper around the C++ library, which is subsequently utilized by the Kotlin side through CInterop.

Solution
This PR adds:

• Project setup of the gRPC client native subproject (with Bazel C++ project for the wrapper)
• First C wrapper of the C++ library
• Initial Kotlin classes to abstract away memory management
• Proof of concept integration of async (callback-based) gRPC calls into Kotlin Coroutines

[Mr3zee]

Please apply Koltin linter rules on all files