Improvement on OutlookMessageLoader

[netoferraz]

OutlookMessageLoader lets users load .msg files stored in the user file system. This works fine, but my proposal here is to work on a new release for this Loader that will add functionality to retrieve emails automatically through Microsoft Graph API. Under the hood, I will use the O-365 package, the same as I've used before to build OneDriveLoader.

What are your thoughts on that, guys?

cc @hwchase17 @vowelparrot