Console scripts: abort all ranks on an uncaught exception (issue #807)

[DLWoodruff]

Closes #807.

The pip console entry points (mpi-sppy-generic-cylinders, mpi-sppy-mrp-generic, mpi-sppy-one-sided-test) bypass python -m mpi4py, whose runner prints the traceback and calls MPI_Abort when a rank raises. Without that, an uncaught exception on one rank leaves the other ranks blocked in a collective and the whole mpiexec job hangs — which is why the docs recommended the -m mpi4py module form over the console scripts.

This PR wraps the three entry-point targets in a new mpisppy/entry_points.py: on an uncaught exception with world size > 1, print the traceback and call MPI.COMM_WORLD.Abort(1), replicating the mpi4py runner's behavior (the "create our own script" idea from the issue, which turned out to need no special launcher — just a ~15-line wrapper). Serial runs re-raise normally so tracebacks and exit codes are unchanged, SystemExit (argparse --help/usage errors) passes through untouched, and the no-mpi4py mock comm in mpisppy.MPI (which has no Abort) is left alone.

Verified end-to-end with a two-rank probe where rank 1 raises while rank 0 waits in a barrier: bare, the job hangs until an external timeout kills it; wrapped, MPI_ABORT fires immediately. Also smoke-tested mpiexec -n 2 mpi-sppy-one-sided-test and a 3-rank farmer run of mpi-sppy-generic-cylinders (both clean), plus new serial unit tests for the wrapper (wired into run_coverage.bash and test_pr_and_main.yml).

Docs: the issue's other half (prefer python -m mpi4py in docs/examples) was mostly done in #803 — 17 of 20 mpiexec ... python doc invocations already used it. This PR converts the two genuine stragglers (debug_utils.rst, the L-shaped example in generic_cylinders.rst) and updates the notes that steered users away from the console scripts for multi-rank runs, since both forms are now equally safe.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 76.38%. Comparing base (3749661) to head (4b5bf2e).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #815      +/-   ##
==========================================
+ Coverage   76.33%   76.38%   +0.04%     
==========================================
  Files         170      171       +1     
  Lines       22628    22650      +22     
==========================================
+ Hits        17274    17301      +27     
+ Misses       5354     5349       -5     

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