Always create RESTObject._short_print_attrs with a default value of
None.

This way we don't need to use hasattr() and we will know the type of
the attribute.

fix(types): prevent __dir__ in RestObject from producing duplicates

Convert _create_attrs and _update_attrs to use a NamedTuple
(RequiredOptional) to help with code readability. Update all code to
use the NamedTuple.

Add the attributes: _create_attrs and _update_attrs to the RESTManager
class. This is so that we stop using getattr() if we don't need to.

This also helps with type-hints being available for these attributes.

Prior to commit 3727cbd21fc40b312573ca8da56e0f6cf9577d08
RESTManager._from_parent_attrs did not exist unless it was explicitly
set. But commit 3727cbd21fc40b312573ca8da56e0f6cf9577d08 set it to a
default value of {}.

So the checks using hasattr() were no longer valid.

Update the checks to check if RESTManager._from_parent_attrs has a
value.

We now create _types = {} in RESTManager class.

By making _types always present in RESTManager it makes the code
simpler. We no longer have to do:
   types = getattr(self, "_types", {})

And the type checker now understands the type.

Add some additional type hints to gitlab/base.py

Don't allow a partially annotated function definition. Either none of
the function is annotated or all of it must be.

Update code to ensure no-more partially annotated functions.

Update gitlab/cli.py with better type-hints. Changed Tuple[Any, ...]
to Tuple[str, ...]

Add type-hints for the variables which are set via self.__dict__

mypy doesn't see them when they are assigned via self.__dict__. So
declare them in the class definition.