Support unrolling functions with scalar arguments inside unrolled loops

[Mark1626]

Closes #418

Summary:

1. Implement the trait Tracker in WFEnv, to track function definitions
   • I've kept the key as Id -> FuncDef. This could have been Id -> Boolean, but it seemed too specific to this scenario for the WFEnv
2. Add a canHaveFunctionInUnroll function which will check from the env if the function can be present inside a unrolled loop
3. Update existing test case (which had scalar arguments) and add a new test case (with an array in the argument)

[rachitnigam]

Awesome, LGTM! Thanks @Mark1626

[rachitnigam]

@Mark1626 BTW, it seems that the CI still doesn't run because of borked permissions. I am going give you write access to the repo so you can directly open branches within the repo and have the CI actually run.