[9.0] feat(Resources): introduce fabric in SSHCE

[aldbr]

Replace the Dirac-specific SSH class by fabric.

BEGINRELEASENOTES
*Resources
CHANGE: Replace SSH by fabric in SSHComputingElement
ENDRELEASENOTES

[fstagni]

Just a note: we do not (yet) have a way to do proper integration test for the Computing Elements, but one may think about adding them to our integration tests setup. Something to think about it, it would be nice if it was in this PR.
It involves creating the "site", with the "CE" (this would be yet another container) and the SiteDirector could send pilots to it.

[aldbr]

Just a note: we do not (yet) have a way to do proper integration test for the Computing Elements, but one may think about adding them to our integration tests setup. Something to think about it, it would be nice if it was in this PR. It involves creating the "site", with the "CE" (this would be yet another container) and the SiteDirector could send pilots to it.

I agree it would great to add integration tests for CEs, at least to test basic features. But it will likely become complex because:

• if we want to test things properly, we need to set up a CE and a Batch System.
• we will have to choose one configuration, but it might not reflect the configuration of the sites in production.

I will give it a try with the SSHCE, let's see.