Support multi node evaluations with Ray in the nemo-run script

[athitten]

Multi node evaluations with Ray need to be done via ray.sub script as described here followed by eval command to launch evaluations.

This feature provides the ability to run multi node and multi instance evaluations with Ray via a single nemo-run script avoiding the hassle of having to run multiple sbtach scripts.

[athitten]

Was able to get this working with mcore, mbridge, nemo installed in a non-editable way in the nemo fw container. However it breaks when used with the nemo fw container as is. This needs to be fixed, @pablo-garay @ko3n1g to help on this.

[athitten]

Fixed the issue with non-editable installs, still needs to be tested on multi node and also make the fix generic and not hard coded.

[athitten]

The code changes are only to the scripts and not the source code. The above changes will be made this week.

[athitten]

Fixed some errors for mnode, still hitting an error related to not all GPUs across nodes being visible (world_size (4) is not divisible by 8). Not a lot of progress here due to limited cluster availability last week, will be resumed this week.