Auto imports should use existing import when possible

[mjbvz]

Environment data

• VS Code version: 1.44.0-insider
• Extension version (available under the Extensions sidebar): 2020.4.68586-dev
• OS and version: MacOS 10.15.3
• Python version (& distribution if applicable, e.g. Anaconda): 3.7.3
• Type of virtual environment used (N/A | venv | virtualenv | conda | ...): NA
• Relevant/affected Python packages and their versions: NA
• Relevant/affected Python-related VS Code extensions and their versions: NA
• Jedi or Language Server? (i.e. what is "python.jediEnabled" set to; more info How to update the language server to the latest stable version vscode-python#3977): Language server
• Value of the python.languageServer setting: Microsoft

Steps to reproduce:

1. For a python file:

import time

sleep(1)

2. Trigger auto imports on sleep and accept

Expected

Auto import use the existing time import

import time

time.sleep(1)

Actual

A second import or time is added

import time
from time import sleep

sleep(1)