Add tuning parameters to stressapttest to replace blank commandline in profile

[AlexW-F]

Summary

Replaces the unused free-form CommandLine parameter in the StressAppTest executor with explicit, typed parameters for memory and thread tuning. The default workload behavior is unchanged.

Changes

• Removed the CommandLine property (was always set to "" in the profile)
• Added three new optional parameters:
  • MemoryInMB — RAM to test in MB (-M flag); defaults to stressapptest auto-detect (~94% of system memory)
  • ThreadCount — number of memory copy threads (-m flag); defaults to stressapptest auto-detect (2 per CPU)
  • CpuStressThreadCount — number of CPU stress threads (-C flag); defaults to none
• Added input validation for the new parameters
• Updated the PERF-MEM-STRESSAPPTEST.json profile to expose the new parameters
• Updated website documentation with parameter descriptions and usage examples

Default behavior

When no new parameters are specified, the generated command line is identical to before:

./stressapptest -s <duration> -l <logfile>

Testing

• Added unit tests for validation of invalid parameter values (zero/negative)
• Added unit tests verifying each new flag appears in the command line when specified
• Added unit test confirming optional flags are omitted when parameters are not set