Add support for SimpleNamespace Intellisense autocompletion

[kbehlers]

Currently SimpleNamespace doesn't populate autocomplete suggestions for set attributes

Environment data

VSCode

Version: 1.47.2
Commit: 17299e413d5590b14ab0340ea477cdd86ff13daf
Date: 2020-07-15T18:18:50.054Z
Electron: 7.3.2
Chrome: 78.0.3904.130
Node.js: 12.8.1
V8: 7.8.279.23-electron.0
OS: Darwin x64 18.7.0

Python Extension

Name: Python
Id: ms-python.python
Version: 2020.7.96456
Publisher: Microsoft

Language Server Settings

{
  "python.languageServer": "Microsoft",
}

Code Example

from types import SimpleNamespace
colors = SimpleNamespace(red='red', blue='blue')
# this should autocomplete, it doesn't find `red` or `blue` as options
colors.red

Screenshot