Support Transaction Context propagation to Concurrency managed threads?

The Jakarta Concurrency 3.0 specification does not requires vendors to support propagation of transaction context to managed threads, and our initial approach was to not support that, but we should evaluate if it's possible and makes sense to provide such feature.

The propagation of transaction context refers to propagate the app thread's transaction to managed executor threads, and there may be 2 levels of support considered for that, following the MicroProfile Transaction Context definitions[1]:
1) Serial propagation, i.e. we allow propagation as long as we only have one thread with the transaction active.
2) Parallel propagation, i.e. we allow propagation and multiple threads may run in parallel with the transaction active.

[1] https://github.com/eclipse/microprofile-context-propagation/blob/master/spec/src/main/asciidoc/txcontext.asciidoc