Support for find_unit and find_unit_by_id

[332fg-raven]

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[332fg-raven]

@rp- If I use List[Group] on groups, mypy shows errors:

dcs/mission.py:1862: error: Incompatible types in assignment (expression has type "list[StaticGroup | ShipGroup | VehicleGroup | PlaneGroup]", variable has type "list[Group[Any, Any]]")  [assignment]
dcs/mission.py:1862: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
dcs/mission.py:1862: note: Consider using "Sequence" instead, which is covariant
dcs/mission.py:1862: error: Unsupported operand types for + ("list[StaticGroup | ShipGroup | VehicleGroup | PlaneGroup]" and "list[HelicopterGroup]")  [operator]

If I use Sequence[Group] as suggested, I get the following:
dcs/mission.py:1862: error: Unsupported operand types for + ("list[StaticGroup | ShipGroup | VehicleGroup | PlaneGroup]" and "list[HelicopterGroup]") [operator]

I could use list[HelicopterGroup | StaticGroup | ShipGroup | VehicleGroup | PlaneGroup] or create a new alias for that.
Using none, does not give any warnings. Let me know if you want to keep it like that or should I revert back.

[rp-]

@rp- If I use List[Group] on groups, mypy shows errors:

dcs/mission.py:1862: error: Incompatible types in assignment (expression has type "list[StaticGroup | ShipGroup | VehicleGroup | PlaneGroup]", variable has type "list[Group[Any, Any]]")  [assignment]
dcs/mission.py:1862: note: "List" is invariant -- see https://mypy.readthedocs.io/en/stable/common_issues.html#variance
dcs/mission.py:1862: note: Consider using "Sequence" instead, which is covariant
dcs/mission.py:1862: error: Unsupported operand types for + ("list[StaticGroup | ShipGroup | VehicleGroup | PlaneGroup]" and "list[HelicopterGroup]")  [operator]

If I use Sequence[Group] as suggested, I get the following: dcs/mission.py:1862: error: Unsupported operand types for + ("list[StaticGroup | ShipGroup | VehicleGroup | PlaneGroup]" and "list[HelicopterGroup]") [operator]

I could use list[HelicopterGroup | StaticGroup | ShipGroup | VehicleGroup | PlaneGroup] or create a new alias for that. Using none, does not give any warnings. Let me know if you want to keep it like that or should I revert back.

I'm surpised mypy can't figure this out, until we have something wrong with the inheritance, but they all share the Group as base type.
But I'm fine with specifying nothing, as it is pretty clear to the reader I guess.