heroic_util: Remove deprecated type hints

[sonic2kk]

This PR removes the deprecated type hints List and Dict imports from typing and replaces them with standard usage of list and dict that are available since Python 3.9. It also introduces some further type hints to other parts of the util file, although incomplete as typing some parts of this is a little complex given our reliance on parsing JSON (ideally we'll eventually have a JSON type alias, and we will more specifically hint in places where we know the structure of the JSON coming back, like if we know certain objects that we're performing .get on are always expected to be dict[str, str] for example). The rationale for further type hinting in the file is to make it easier for unit tests once we eventually get to that stage.

[DavidoTek]

Thanks!

although incomplete as typing some parts of this is a little complex given our reliance on parsing JSON (ideally we'll eventually have a JSON type alias, and we will more specifically hint in places where we know the structure of the JSON coming back, like if we know certain objects that we're performing .get on are always expected to be dict[str, str] for example).

If we know that the returned type will be dict[str, str] we can use that. The only problem is that the JSON could potentially change and the data could be dict[str, Any] (or even Any).
Ideally, we would check if the type is correct before returning it. Not sure if it is worth the effort (I would like if Python had something like https://zod.dev integrated... 😄)
-> I think it is okay to type-hint dict[str, str] in the future if we assume that is the expected type.