Additional operands for GoogleAPI for .json management

V4.1.0 introduces two new optional operands for the invocation of both the standard PHPMailer email application and for the complete replacement of a PHPMailer application by the wrapper front-end (c. below). There operands allow the developer to specify a name for the .json credentials file and/or whether the wrapper should dynamically build this .json file or use an already-built one, created  either by Google (its standard download) or by the developer.

Added support for GoogleAPI

Update SendOauth2A.php

Minor cosmetic change

Create SendOauth2A-invoke.php

Add files via upload

Update SendOauth2D.php

Update SendOauth2D.php

oauth2-google version now >=4.0.0

Update oauth2-google version from >=3.0.4 to >=4.0.0 as my bash shell PHP version is now upgraded to 7.3 and not the previous 5.6 (the http version was fine at 7.3.5)

Update README.md

Remove 2 x providers