Add ibrun/aprun/flux run/prun, drop legacy jsrun/lrun/runjob

[jeanbez]

Fixes #170.

The schema's `mpi.command` enum previously listed `mpirun`, `mpiexec`, `srun`, `jsrun`, `runjob`. Two problems: several currently-used launchers were missing, and three of the listed launchers target systems that are decommissioned or actively winding down.

Additions

• ibrun — TACC (Stampede3, Frontera, Lonestar6).
• aprun — Cray ALPS (remaining XC40-class systems).
• flux run — LLNL Tioga (ATS-4), coming to El Capitan.
• prun — Cray PALS.

Removals

• runjob — BlueGene/Q, last system decommissioned around 2019.
• jsrun — LSF launcher on Summit/Sierra. Summit decommissioned Nov 2024, Sierra 2023.
• lrun — LLNL Sierra/Lassen wrapper over jsrun; same fate.

Users on any of the removed systems can re-add the entry locally, or fall back to the raw `command` string once the enum is opened up.

Touchpoints

1. `schemas/h5bench-config.schema.json`: new enum `[mpirun, mpiexec, srun, ibrun, aprun, flux run, prun]`. Description spells out the per-launcher rank-flag mapping.
2. `src/h5bench.py` `check_parallel`: shell-blacklist now matches the enum.
3. `src/h5bench.py` `prepare_parallel`: dispatches the four new launchers to `{cmd} -n `.

Tests

Parametrised test in `test_driver_unit.py` covers each of the four new launchers via the `ranks:` path.

Test plan

• Unit tests pass (4 new parametrised cases).
• Schema still accepts existing sample configs.
• Schema rejects `command: "jsrun"` and `command: "runjob"` (the removals).
• A `{"command": "ibrun", "ranks": "4"}` config produces `ibrun -n 4`.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.87%. Comparing base (94f11ed) to head (0470824).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #171      +/-   ##
===========================================
+ Coverage    58.85%   58.87%   +0.01%     
===========================================
  Files           14       14              
  Lines         6062     6064       +2     
  Branches      1427     1428       +1     
===========================================
+ Hits          3568     3570       +2     
  Misses        1917     1917              
  Partials       577      577              

Flag	Coverage Δ
c	58.87% <100.00%> (+0.01%)	⬆️
python	58.87% <100.00%> (+0.01%)	⬆️

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