Additional options for GCP job specification

[RobertTLange]

Add a set of options to job specification single_job_args for GCP:

• [x] Option not to copy over/delete code directory to/from GCS bucket.
• [ ] Base machine type. By default this is n2-highcpu-<num_cores>.
• [x] Allow for additional install setup via install_setup.sh (not only via pip install -r .
• [ ] Support docker and containerization.
• [ ] Support time out termination of GCP VMs. Locally terminate/delete job.
• [x] Launch of GCP job from Slurm/SGE cluster for more network robustness.
• [x] Option to exclude directory from being uploaded

[RobertTLange]

Move this to mle-scheduler