Set permissions for Omega CTest downloads

[xylar]

Without this, the files are being left with permissions such that only the person downloading the file can read them.

To support this, we move code for updating permissions to the shared io module

Checklist

• Developer's Guide has been updated
• API documentation in the Developer's Guide (api.md) has any new or modified class, method and/or functions listed
• Documentation has been built locally and changes look as expected
• Testing comment in the PR documents testing used to verify the changes

fixes #198

[xylar]

@sbrus89, could you delete the following directory on Perlmutter?

/global/cfs/cdirs/e3sm/polaris/ocean/broken_omega_ctest

I had to move it aside because only you can access it because of the bug that this PR aims to fix.

[xylar]

Testing

I ran the Omega CTests on Perlmutter-CPU with Gnu. I removed the omega_ctest shared directory so that files were re-downloaded. As expected, the permissions were set to:

xylar@perlmutter:login25:/global/cfs/cdirs/e3sm/polaris/ocean> ls -lah omega_ctest/
total 86M
drwxrwxr-x 2 xylar e3sm 4.0K Jul 12 01:56 .
drwxrwxr-x 5 xylar e3sm 4.0K Jul 12 01:56 ..
-rw-rw-r-- 1 xylar e3sm 3.6M Jul 12 01:56 cosine_bell_icos480_initial_state.230220.nc
-rw-rw-r-- 1 xylar e3sm  80M Jul 12 01:56 ocean.QU.240km.151209.nc
-rw-rw-r-- 1 xylar e3sm 2.5M Jul 12 01:56 PlanarPeriodic48x48.nc

[sbrus89]

@sbrus89, could you delete the following directory on Perlmutter?

/global/cfs/cdirs/e3sm/polaris/ocean/broken_omega_ctest

I had to move it aside because only you can access it because of the bug that this PR aims to fix.

Just took care of this @xylar, thanks for letting me know.

[xylar]

@sbrus89, great, thank you!