Indy OAuth authentication over SASL

[Remy Lebeau 1421]

FYI, this morning I checked in a new 'sasl-oauth' branch in Indy's repo, which includes a new 'IdSASLOAuth.pas' unit for SASL classes for OAUTH10A, OAUTHBEARER, and XOAUTH2 for TIdDICT, TIdPOP3, TIdSMTP, and TIdIMAP4.  They are still a work in progress (ie, no parsing of response JSON yet), and you are responsible for obtaining the OAuth tokens externally (ie, over HTTP), but once you have the tokens then you can use these SASLs to login to the DICT/POP3/SMTP/IMAP servers.

Edited June 1, 2022 by Remy Lebeau