Implement Modern Auth to use IMAP connector with Exchange

In October 2020, Microsoft will turn off Basic Auth. So our current IMAP connector will not work any more with Exchange. We have to make the required changes to use the new API (Modern Auth / Microsoft Identity SQK) to still provide the connection to Exchange

https://developer.microsoft.com/en-us/office/blogs/microsoft-authentication-libraries-for-java-and-python-are-now-generally-available/