Add ability to migrate content in Google Drive under Computer (i.e., when Google Drive Desktop is used to sync files to their Google Drive).

When performing a migration using ShareGate Desktop from Google Drive to OneDrive/SharePoint, there are Google Drive users using Google Drive Desktop to sync files to their Google Drive. These files synced from the desktop to the user's Google Drive do not appear in the ShareGate Desktop source listing of files. The sync'd content contributes to the overall Google Drive storage size.

Google Drive for Desktop syncs via mirroring or streaming. In both cases documents are stored in the cloud. (Reference: https://support.google.com/drive/answer/10838124?hl=en).