spdlog and SDL_Log ... and user log

[Raffaello]

this as a library should allow to integrate a 3rd parties loggers too..

also SDL_Log are still produced using SDL and spdlog basically is only generating log SDL_CATEGORY_APPLICATION related.

review it.

[Raffaello]

it might be better to use only SDL logs for this as a library and use the channel audio in most cases to publish logs.

and spdlog can be used instead in the examples eventually.

or give an interface/ integartion with a user application to use spdlog