Add support for the LSF scheduler

[vkarak]

I got a couple of requests to implement support for the LSF scheduler. We could do a basic implementation as with PBS that we could test with the Slurm LSF wrappers.

[AnibalMG]

Any progress on this?

[vkarak]

Hi @AnibalMG, nothing so far. Our key focus has been in redesigning the configuration of the framework, which will unblock several other issues. I don't know about your bandwidth, whether you would like to contribute this backend. I could guide you through the necessary steps you need to do. It should not be difficult; we recently had an external contribution for a Torque backend in #1172.