Support Drupal Symfony Mailer

[elgandoz]

What in this template can be improved or added as a feature?

The Drupal Symfony Mailer module has become the de-facto solution for managing HTML emails in Drupal 10, and there are ongoing discussions about incorporating Symfony Mailer into Drupal core (Issue #3380476).
To align with this shift, I suggest adding the necessary configuration adjustments to the Drupal 10 Platform.sh template, in order to support this otherwise required configuration.

What exactly should be updated?

Add a custom command for the configuration mailer_sendmail_commands.
The command will be taken by the sendmail_path in the ini file from the platform.

$settings['mailer_sendmail_commands'] = [
  ini_get('sendmail_path'),
];

See more:
https://www.drupal.org/docs/contributed-modules/drupal-symfony-mailer/getting-started#s-platformsh

NB: The documentation suggest to add the parameters -t -i, but I noticed those are already inherited by the ini variable, hence they're not necessary.

How important is this feature to you?

Not too important, it can be easily added in each own build, but it took a moment to resolve this specific issue and I hope it could simplify the life for someone else using this module, which I believe is very likely.

Additional context