Fix type hint

[thislight]

This pull request is intended to revised existing type hint in this project and fix all problems about typing reported by mypy.

Including fixes:

• __eq__() and __ne__() accept any object as the argument.
• new type comment for decorator builder
• improve type comments
• fix errors in terms.py, utils.py, dialects.py

TODO:

• find workarounds for old python (pypika requires python 3.6+)

[thislight]

I discover a failed test for terms.py:

ERROR: test__criterion_replace_table_with_value (pypika.tests.test_internals.TablesTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "~/Project/pypika/pypika/tests/test_internals.py", line 16, in test__criterion_replace_table_with_value
    self.assertEqual(c.left, table)
  File "/usr/lib64/pypy3.9/unittest/case.py", line 837, in assertEqual
    assertion_func(first, second, msg=msg)
  File "/usr/lib64/pypy3.9/unittest/case.py", line 827, in _baseAssertEqual
    if not first == second:
  File "~/Project/pypika/pypika/terms.py", line 265, in __eq__
    return BasicCriterion(Equality.eq, self, Term._assert_guard(self.wrap_constant(other)))
  File "~/Project/pypika/pypika/terms.py", line 301, in _assert_guard
    raise TypeError("expect Term object, got {}".format(type(v).__name__))
TypeError: expect Term object, got Table

I wonder if the original behaviour in the test is intended.