Releasing a Lando Testing Environment for PHPMailer

[SirLouen]

To be more comfortable helping out with some contributions for PHPMailer, I found that having to set up everything locally was a little painful

So I've been working on a Lando dev environment here:
https://github.com/SirLouen/phpmailer-dev

Still some work to be done (and some PR to get through to make it a little more comfortable).

The idea was getting something like this:

Which is a lot better than having two dozen skipped tests by default when we are working on something entirely different, plus not having to setup any mail servers which generally is also a little painful (specially if you are going back and forth between different projects)

In this case, I'm using mailpit and relayed postfix (for now is just being used for the Cram-MD5 test which happens to be incomplete! but it may have more use as mailpit doesnt have full mailing features, and it requires some relaying to make things not supported by default, work). I love mailpit because it feels like mailhog 2.0 and I can see test results straight on the web inbox. I will also be setting up next a Qmail container just for the (single for now) qmail test.

Don't hesitate to comment on any improvements.