Set Store hostname in SmtpOptions

[MennoTammens]

Description (*)

Laminas SMTP Transport Options has the option to set the name of the local client hostname, this is the name the client uses to identify itself to the mail server (HELO command).
The default setting is localhost, but some spam filters don't like that (SpamAssassin rule HELO_LOCALHOST)

This patch uses the hostname of the website as name in the SmtpOptions.

Manual testing scenarios (*)

1. Send test mail
2. Open the mail headers
3. Before this patch:
   Received: from localhost (real.host.name [1.2.3.4]) by mx.mail.server;
4. With this patch:
   Received: from store.host.name (real.host.name [1.2.3.4]) by mx.mail.server;

Questions or comments

Should this be configurable? Are there situations where this solution is worse than localhost?