Cleaner forms submit logic

[Raruto]

Reorganization of the code within the Forms::submit function to allow finer extensibility by other developers.

All changes are backward compatible.

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List of changes:

• added 'forms.submit.email' event to allow finer filtering of sent emails (eg. to avoid creating a specific template for each newly created form):

// Filter email content

$this->app->trigger('forms.submit.email', [$form, &$data, $frm, &$body, &$options]);

• added &$response parameter to 'forms.submit.after event to allow finer filtering of returned data (I don't really like phpmailer errors being sent directly to the browser)

// Filter submission response

$this->app->trigger('forms.submit.after', [$form, &$data, $frm, &$response]);

• replace $this->app->renderer->file with $this->app->view (to allow access to app viewvars in email templates)

// Load custom email template

if ($template = $this->app->path("#config:forms/emails/{$form}.php")) {
    $body = $this->app->view($template, ['data' => $data, 'frm' => $frm]);
}

• added a default modules/Forms/views/api/email.php template (also useful for help people understand how to create their owns)

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Side notes

I just discovered the existence of this method PHPMailer::validateAddress($address, $patternselect), maybe this section could be further simplified?

cockpit/modules/Forms/bootstrap.php

Lines 271 to 280 in 722393b

	$emails = array_map('trim', explode(',', $frm['email_forward']));
	$filtered_emails = [];
	foreach ($emails as $to){
	// Validate each email address individually, push if valid
	if ($this->app->helper('utils')->isEmail($to)){
	$filtered_emails[] = $to;
	}
	}