Monaco autocompletion should return suggestion content after the last dot

[Barry T]

Application or Package Used
Regression within the nteract monaco-editor package.

Describe the bug
Monaco autocompletion should return suggestion content after the last dot. Today, there are cases that a kernel when given "suggestion1.itemA" text and typing "." that it will suggest the full path of "suggestion.itemA.itemB" instead of just "itemB". Another case is where given "suggestion1.itemA.it" text and typing "e" will suggest the full path of "suggestion.itemA.itemB" instead of just "itemB".

This is a regression. We used to handle the scenarios above.

Regression caused by this commit:
867dd72#diff-a55f42bbb6045da0f938cd149964b418f08e33fa143062d8cecaaeba4a996373

To Reproduce
Steps to reproduce the behavior:

Pre-requisite:
0. Install Python kernel 3.6 and install azureml-sdk (via pip install azureml-sdk)

1. Open a notebook with nteract and enable using monaco editor instead of code mirror.
2. Create a cell and type: from azureml.core.a

Expected behavior
Autocompletion suggests "authentication" as an item instead of "azureml.core.authentication" as an item.

Desktop (please complete the following information):

• OS: [e.g. macOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Additional context
Add any other context about the problem here.