Add "session_import_settings" configuration value see BT#15081

This option sets default parameters in the main/session/session_import.php

main/install/configuration.dist.php

@@ -1024,9 +1024,18 @@ VALUES (2, 13, 'session_courses_read_only_mode', 'Lock Course In Session', 1, 1,
 // Allow my personal files link in the homepage
 // $_configuration['allow_my_files_link_in_homepage'] = false;
 
+// This option sets default parameters in the main/session/session_import.php
+/*$_configuration['session_import_settings'] = [
+    'options' =>  [
+        'session_exists_default_option' => '1',
+        'send_mail_default_option' => '1',
+    ]
+];*/
+
 // ------ Custom DB changes (keep this at the end)
 // Add user activation by confirmation email
 // This option prevents the new user to login in the platform if your account is not confirmed via email
 // You need add a new option called "confirmation" to the registration settings
 //INSERT INTO settings_options (variable, value, display_text) VALUES ('allow_registration', 'confirmation', 'MailConfirmation');
 // ------ (End) Custom DB changes
+

main/session/session_import.php

@@ -511,6 +511,17 @@ $form->addElement('checkbox', 'sendMail', null, get_lang('SendMailToUsers'));
 $form->addButtonImport(get_lang('ImportSession'));
 
 $defaults = ['sendMail' => 'true', 'file_type' => 'csv'];
+
+$options = api_get_configuration_value('session_import_settings');
+if (!empty($options) && isset($options['options'])) {
+    if (isset($options['options']['session_exists_default_option'])) {
+        $defaults['overwrite'] = $options['options']['session_exists_default_option'];
+    }
+    if (isset($options['options']['send_mail_default_option'])) {
+        $defaults['sendMail'] = $options['options']['send_mail_default_option'];
+    }
+}
+
 $form->setDefaults($defaults);
 
 Display::return_message(get_lang('TheXMLImportLetYouAddMoreInfoAndCreateResources'));