SendMail actor should be updated to handle OAuth 2.0

[cxbrooks]

Note: the issue was created automatically with bugzilla2github tool

Original bug ID: BZ#535
From: @cxbrooks
Reported version: 11.0.devel
CC: pt-dev@chess.eecs.berkeley.edu

[cxbrooks]

If you are using Google as your smtp provider, then you may need to modify your Google account to
See https://support.google.com/accounts/answer/6010255?hl=en
Allow less secure apps to access your account says:

This is because this actor does not support OAuth 2.0.
https://support.google.com/a/answer/6260879?hl=en
Allow less secure apps to access accounts Frequently Asked Questions (FAQ)
says:

What criteria is used to identify an application as being “less secure”?

Applications that rely on plain username/password
authentication to access an account programmatically are
considered less secure than those using modern day security
standards such as OAuth 2.0.

The class comment in the actor has been updated with the above text.