Handle MPI init/finalize failures

[aobolensk]

• check the return codes of MPI_Init and MPI_Finalize
• abort and return the error code if MPI setup/teardown fails
• document new behaviour in runners header

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 92.37%. Comparing base (81c3284) to head (2af1726).
Report is 6 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #447   +/-   ##
=======================================
  Coverage   92.37%   92.37%           
=======================================
  Files          11       11           
  Lines         354      354           
  Branches      124      113   -11     
=======================================
  Hits          327      327           
  Misses         10       10           
  Partials       17       17           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.