Ulimit: Programatically increase softlimit to hard-limit

[ax3l]

In post-processing, we often have less resources as in writing.
We often reach the ulimit -n for open files on Jupyter or ParaView or VisIt or scripts for sub-files.

This can often be work-arounded by increasing the ulimit -n ... soft-limit closer to the hard-limit of a machine.

Idea discussed today with @pnorbert @franzpoeschel:
Let's programmatically increase the soft-limit of a ADIOS2-enabled process to like 90% or 100% of the hard-limit for open files.

X-ref:

• MaxOpenFilesAtOnce for BP4? #3371
• ADIOS2 v2.8.1+: MaxOpenFilesAtOnce openPMD/openPMD-api#1300

[pnorbert]

This has been added to master branch with #3376. BP3, BP4 and BP5 now will raise the softlimit to the hardlimit automatically.
Can you please test this out on your datasets. What about Windows? I made a blind call for windows to raise the limit but I don't know if it works.