Fix to_dict()

[ensko]

Fixes #23, based on #24 for obvious reasons

Note that test_core/test_grades.py is currently failing, even before this PR -- maybe something to do with Moodle 5.0 compatibility?

This PR reimplements to_dict() and changes some behavior that was not depended upon:

• Due to recursion, the function could previously accept any value and also accept a name parameter. The actual recursion is now in a nested function, so I

  • removed the name parameter.
  • require that the passed data are a dictionary. A HTTP request always has named parameters, only the nested values will eventually not be dicts

  This means that you can't pass a @attr.s class directly to the function. You can see the commented regressed test case here:
  

  moodlepy/tests/test_utils/test_helper.py

  Lines 44 to 46 in 6e580f1

  	# attr class
  	# result = to_dict(MyAttrClass(x=1, y=2))
  	# assert result == { 'x': 1, 'y': 2 }

  
  If you have concerns about this, I can of course also handle this case.

• I didn't know what the purpose of these lines were so I didn't preserve them:
  

  moodlepy/moodle/utils/helper.py

  Lines 31 to 33 in 760fb0c

  	# Check if data required name prefix
  	if hasattr(data, "name"):
  	out_key += f"[{getattr(data, 'name')}]"

  
  because of this, I have marked this PR as a draft. It hasn't caused regressions, though.

You can take a look at cd3d959 to see what previously failing test cases now succeed. Additionally, in 2e552b8 I edited the test case to fail as described in #23.

Beyond that one calendar test case, I have not tested that the new behavior matches PHP's expectations of form encoded data, so I'd ask you to look over the test cases.