Make configurable adding the Mock Lambda Test Tool to launchsettings

**Is your feature request related to a problem? Please describe.**
Toolkit automatically adds the entry to launchsettings whether you want it or not.
Have to either disable the whole toolkit to prevent this or go through all projects in a solution to remove these entries to avoid getting them checked in.

**Describe the solution you'd like**
Make it configurable or just have a sample template in the documentation the user can manually add.

**Describe alternatives you've considered**
Not seeing any alternatives to having to clean up all the project files from these unwanted entries.

No file or test is named. Start by locating the code that automatically adds the Mock Lambda Test Tool entry to launchsettings, then inspect how toolkit settings and documentation are organized. Done means users can prevent the automatic entry or follow a documented manual-template path without disabling the whole toolkit.

Written by the indexing model from the issue text.