Embed settings in the internal CoreInstance

[silvanocerza]

Currently configs used by the Arduino CLI are stored in a global struct, both when running in daemon or command line mode.

This behaviour has some issues since it prevents gRPC consumers to use different configs for different clients connected to it, this means that if a client wants to change settings they change for all clients.

The solution is to embed the settings in the CoreInstance and access them only through it. This will enhance a lot how settings are handled and also make it easier to write unit tests for certain code parts.

[silvanocerza]

Part of this task is already been done on branch scerza/embedding-settings.

[umbynos]

Unfortunately this branch is quite old now, we are going for a similar approach in the future maybe.