Follow-up: MPI + UCX integration examples (PR #434)

[goodboy]

Follow-up from PR #434

Tracking integration example work identified in the
per-actor-inherit-parent-main PR.

• Add MPI integration
  example Start by wrapping a few of the mpi4py tutorial
  examples to demonstrate inherit_parent_main=False usage
  with MPI's process spawning model.

  • @mahmoudhas already started (finished?) this in Add per-actor parent-main inheritance opt-out #434,

    • https://github.com/goodboy/tractor/pull/434/changes#diff-1553e4fb6ef1d430f3d24fa7dfcb0050764b9bf91a9a238c2a88691fae2e6545

  • consider a dynamic py-code-in-module generator API, possibly
    alike pytest's tmp_path fixture?

    • see Add per-actor parent-main inheritance opt-out #434 (comment)
      and the relevant pytest docs,

      • https://docs.pytest.org/en/stable/reference/reference.html#std-fixture-tmp_path
      • https://docs.pytest.org/en/stable/how-to/tmp_path.html#tmp-path

    • also obviously (will) relate(s) to Hot-code-reload: can we do it git driven? #360

• Add UCX /
  ucxx integration example
  Glean naive examples from the ucxx benchmark
  scripts to show tractor + UCX transport interop.

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(this tracking issue was generated by claude-code)