gRPC service support + use SDK as Conan package

[BjoernAtBosch]

Description

• Add support for using gRPC-based services as defined in app manifest
• Use C++ SDK as (local) Conan package (removing SDK subrepo)

Issue ticket number and link

AB#16326 (task 16813)

Checklist

• [ ] Vehicle App can be started with dapr run and is connecting to vehicle data broker

• [ ] Vehicle App can process MQTT messages and call the seat service

• [ ] Vehicle App can be deployed to local K3D and is running

• [ ] Created/updated tests, if necessary. Code Coverage percentage on new code shall be >= 70%.

• [ ] Extended the documentation in Velocitas repo

• [ ] Extended the documentation in README.md

• [ ] Devcontainer can be opened successfully

• [ ] Devcontainer can be opened successfully behind a corporate proxy

• [ ] Devcontainer can be re-built successfully

• [ ] Release workflow is passing