Track Context-scoped attributes addition

[carlosalberto]

This is the tracking branch for the Context-scoped attributes OTEP (#4931) . We want to track all issues that directly or indirectly are part of this whole initiative:

• Prototype context scoped attributes #5170

IMHO it would be a good idea to have these initial children issues:

1. Context-scoped attributes added to the Context layer.
2. Context-scoped attributes added to tracing (depending on 1).
3. Context-scoped attributes added to metrics (depending on 1).
4. Context-scoped attributes added to logging (depending on 1).

WDYD @jack-berg ?