[FEATURE ADD] Fix up PoolExecutor wrapper class

[HunterAP23]

Describe the feature that is being tested/implemented
Add the following functionality to the PoolExecutor wrapper class:

• Wraps around combination of Thread and Process pool classes
• Raise "not implemented" exception when using functions not available on the specified class type
• Add optional variable used when creating thread pools to act as a multiplier for the specified number of threads (default multiplier is 5).
  • IE: if the given number of threads was 6, and the multiplier was 1.5, then the total number provided to the super ThreadPoolExecutor would be 9.
  • This should only be applied to ThreadPoolExecutors, NOT ProcessPoolExecutors

List any relations to other issues in this repository or in other repositories
N/A