Consider multi-threading for default writer

Currently multi threading is not considered. This means if the same id is used from multiple threads, it could be possible that spans / trace points are mixed and analysis is no longer possible.

These are the items we need to solve this issue:

• An example or test that demonstrate if there is an issue
• A concept how to solve this issue
• An implementation of this issue as well as fixing / modification of the tests or examples created for this issue