Since Python 3.9, type hinting has become a little less awkward, as for
collection types one doesn't need to import the corresponding
capitalized types (`Dict`, `List`, `Set`, `Tuple`, ...) anymore, but can
use the built-in types directly. [1] [2]
This commit applies the replacement for all Python scripts (i.e. in the
contrib and test folders) for the basic types:
- typing.Dict -> dict
- typing.List -> list
- typing.Set -> set
- typing.Tuple -> tuple
[1] https://docs.python.org/3.9/whatsnew/3.9.html#type-hinting-generics-in-standard-collections
[2] https://peps.python.org/pep-0585/#implementation for a list of type
This is important to make sure that we're not testing tools different
from the one we're building with.
Introduce determine_wellknown_cmd, which encapsulates how we
should handle well-known tools specification (IFS splitting, env
override, etc.).
