Fixing the generated vtr_flow.sh scripts

[MohamedElgammal]

Description

The run_vtr_task.py script can generate vtr_flow.sh scripts by adding -system scripts option. Each script runs one (design, arch) pair of the specified task
In this PR, some bugs of this generation process is fixed:

• the script now generates a correct vpr command
• the script now generates the full cartesian product runs of the designs, architectures, and script parameters.
• the script adds executable permission to the generated shell scripts

Related Issue

Motivation and Context

The generated shell scripts can be used to run multiple VPR runs in parallel on a large cluster.

How Has This Been Tested?

Types of changes

• Bug fix (change which fixes an issue)
• New feature (change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

[vaughnbetz]

Should add more commenting around the "scripts" option. For example around line 310, "elif args.system == "scripts":"
you could describe what this argument does.
Same thing for the documentation of the command line option --system (line 160 or so):
The help says "What system to run this on" which isn't very detailed. Should explain what the --system scripts option does somewhere, likely in the help. Details might be in a comment block.
parser.add_argument(
"-system",
choices=["local", "scripts"],
default="local",
help="What system to run the tasks on.", // can improve this.
)

[vaughnbetz]

The clang errors should be fixed already (was an unrelated missing #include). Updating the branch to kick that off.

There are two scripts with python lint errors that should be fixed.

E.g.: vtr_flow/scripts/python_libs/vtr/task.py has lint errors
************* Module vtr.task
vtr_flow/scripts/python_libs/vtr/task.py:463:4: W0612: Unused variable 'num_spaces_before' (unused-variable)
vtr_flow/scripts/python_libs/vtr/task.py:464:4: W0612: Unused variable 'num_spaces_after' (unused-variable)

[vaughnbetz]

Still some python lint errors:
vtr_flow/scripts/run_vtr_task.py has lint errors
************* Module run_vtr_task
vtr_flow/scripts/run_vtr_task.py:126:0: C0301: Line too long (157/100) (line-too-long)
vtr_flow/scripts/run_vtr_task.py:303:0: C0301: Line too long (102/100) (line-too-long)
vtr_flow/scripts/run_vtr_task.py:354:22: W0613: Unused argument 'args' (unused-argument)
vtr_flow/scripts/run_vtr_task.py:403:7: C0121: Comparison 'metrics == None' should be 'metrics is None' (singleton-comparison)
vtr_flow/scripts/run_vtr_task.py:418:7: C0121: Comparison 'metrics == None' should be 'metrics is None' (singleton-comparison)
vtr_flow/scripts/run_vtr_task.py:24:0: W0611: Unused find_longest_task_description imported from vtr (unused-import)

[vaughnbetz]

Waiting for CI to go green ...
@MohamedElgammal : would also be good to add more commenting, as noted above. Can merge without that though, but it would be good to comment sooner than later since it tends to get forgotten otherwise.

[MohamedElgammal]

@vaughnbetz added more commenting and fixed all python linting issues. Will merge into master.