next: Consolidate generic base types

[elycruz]

We're using any for base function types and we're also using redundant types in some places (PredForSlice, SlicePred, etc.). Aforementioned types need to be cleaned up, and/or, consolidated.

Acceptance Criteria

• Consolidate any Slice Predicate types (PredForSlice, SlicePred, etc.).
• Where we could introduce flexible base (generic) types, for native built-ins we should (unless they already exist) - Look into methods receiving/returning any - Do not add typings where inference can easily tell what the value is (instead use generics (in these cases) if at all possible).
  Modules updated:
  • 'boolean/'
  • 'function/'
  • 'list/'
  • 'number/'
  • 'object/'
  • 'string/'
  • 'types/'
  • ...