### Summary

Add type hints to `ansible.parsing.dataloader::DataLoader`

### Issue Type

Feature Idea

### Component Name

lib/ansible/parsing/dataloader.py
from __future__ import (absolute_import, division, print_function)
__metaclass__ = type
import copy
import os
import os.path
import re
import tempfile
from ansible import constants as C
from ansible.errors import AnsibleFileNotFound, AnsibleParserError
from ansible.module_utils.basic import is_executable
from ansible.module_utils.six import binary_type, text_type
from ansible.module_utils.common.text.converters import to_bytes, to_native, to_text
from ansible.parsing.quoting import unquote
from ansible.parsing.utils.yaml import from_yaml
from ansible.parsing.vault import VaultLib, b_HEADER, is_encrypted, is_encrypted_file, parse_vaulttext_envelope
from ansible.utils.path import unfrackpath
from ansible.utils.display import Display
display = Display()
RE_TASKS = re.compile(u'(?:^|%s)+tasks%s?$' % (os.path.sep, os.path.sep))
class DataLoader: