Add support for OAR Scheduler

[ychiat35]

Types of changes

• New feature (non-breaking change which adds functionality)

Summary

The Oar scheduler is widely used in France, including mesocentre supercomputers (e.g., GRICAD), INRIA supercomputers, Grid5000 testbed and other platforms.

This PR adds support for the OAR Scheduler, following the implementation made for Slurm.

Checklist

• [ ] I have added tests to cover my changes (if necessary)
• [ ] I have updated documentation (if necessary)

[codecov[bot]]

Codecov Report

Attention: 103 lines in your changes are missing coverage. Please review.

Comparison is base (0e3d33c) 83.52% compared to head (e54491c) 81.86%.

:exclamation: Current head e54491c differs from pull request most recent head 3cadef2. Consider uploading reports for the commit 3cadef2 to get more accurate results

Files	Patch %	Lines
pydra/engine/workers.py	7.20%	103 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #713 +/- ## ========================================== - Coverage 83.52% 81.86% -1.67% ========================================== Files 23 23 Lines 4990 5101 +111 Branches 1429 1453 +24 ========================================== + Hits 4168 4176 +8 - Misses 814 917 +103 Partials 8 8 ``` | [Flag](https://app.codecov.io/gh/nipype/pydra/pull/713/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipype) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/nipype/pydra/pull/713/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipype) | `81.86% <7.20%> (-1.67%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=nipype#carryforward-flags-in-the-pull-request-comment) to find out more.

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[djarecka]

@ychiat35 - thank you for adding this worker. Would it be possible to test it within a container?

[ychiat35]

@ychiat35 - thank you for adding this worker. Would it be possible to test it within a container?

Hi, I'm trying to use oar-docker to do that. It is still WIP (I have to find more time doing that) but I noticed that the oar-docker solution requires cgroup v1, so I have to run on ubuntu-20.04 but not ubuntu-latest. Is this a problem for you?