Add PEFT scheduler implementation

[jasonlopez5]

What?

PEFT includes optimistic estimates of future computation costs through the Optimistic Cost Table (OCT). These estimates are then used to guide processor selection so that scheduling decisions consider future execution costs rather than purely greedy choices.

Why?

Adding PEFT expand's SAGA's library of scheduling algorithms, allowing for comparisons with existing schedulers implemented.

How?

• Implemented the PEFT scheduler in src/saga/schedulers/peft.py
• Implemented OCT computation to estimate remaining costs from task to exit node.
• Registered the scheduler in src/saga/schedulers/init.py so it is included in the scheduler tests

Testing?

The scheduler is included in the existing scheduler tests by registering PEFTScheduler() in the list of schedulers used by the tests.

Reference

H. Arabnejad and J. G. Barbosa,
"List Scheduling Algorithm for Heterogeneous Systems by an Optimistic Cost Table,"
IEEE Transactions on Parallel and Distributed Systems,
vol. 25, no. 3, pp. 682–694, March 2014.
https://doi.org/10.1109/TPDS.2013.57