Revert back to QLineEdit for "Run external program". Closes #7800

1. Using FileSystemPathEdit is not entirely correct, as it only always
shows false warnings when parameters are present.
2. FileSystemPathEdit::selectedPath() modifies the path to unix format,
in this specific case, we need to faithfully execute what user inputted.
3. Given the above it is reasonable to revert back to QLineEdit, as it
is just sufficient in functionality and doesn't modifiy the inputs.

src/gui/optionsdlg.cpp

@@ -269,7 +269,7 @@ OptionsDialog::OptionsDialog(QWidget *parent)
     connect(m_ui->mailNotifUsername, &QLineEdit::textChanged, this, &ThisType::enableApplyButton);
     connect(m_ui->mailNotifPassword, &QLineEdit::textChanged, this, &ThisType::enableApplyButton);
     connect(m_ui->autoRunBox, &QGroupBox::toggled, this, &ThisType::enableApplyButton);
-    connect(m_ui->autoRun_txt, &FileSystemPathEdit::selectedPathChanged, this, &ThisType::enableApplyButton);
+    connect(m_ui->autoRun_txt, &QLineEdit::textChanged, this, &ThisType::enableApplyButton);
 
     const QString autoRunStr = QString("%1\n    %2\n    %3\n    %4\n    %5\n    %6\n    %7\n    %8\n    %9\n    %10\n%11")
                                .arg(tr("Supported parameters (case sensitive):"))
@@ -589,7 +589,7 @@ void OptionsDialog::saveOptions()
     pref->setMailNotificationSMTPUsername(m_ui->mailNotifUsername->text());
     pref->setMailNotificationSMTPPassword(m_ui->mailNotifPassword->text());
     pref->setAutoRunEnabled(m_ui->autoRunBox->isChecked());
-    pref->setAutoRunProgram(m_ui->autoRun_txt->selectedPath().trimmed());
+    pref->setAutoRunProgram(m_ui->autoRun_txt->text().trimmed());
     pref->setActionOnDblClOnTorrentDl(getActionOnDblClOnTorrentDl());
     pref->setActionOnDblClOnTorrentFn(getActionOnDblClOnTorrentFn());
     TorrentFileGuard::setAutoDeleteMode(!m_ui->deleteTorrentBox->isChecked() ? TorrentFileGuard::Never
@@ -847,7 +847,7 @@ void OptionsDialog::loadOptions()
     m_ui->mailNotifPassword->setText(pref->getMailNotificationSMTPPassword());
 
     m_ui->autoRunBox->setChecked(pref->isAutoRunEnabled());
-    m_ui->autoRun_txt->setSelectedPath(pref->getAutoRunProgram());
+    m_ui->autoRun_txt->setText(pref->getAutoRunProgram());
     intValue = pref->getActionOnDblClOnTorrentDl();
     if (intValue >= m_ui->actionTorrentDlOnDblClBox->count())
         intValue = 0;

src/gui/optionsdlg.ui

@@ -1213,7 +1213,7 @@
               </property>
               <layout class="QVBoxLayout" name="verticalLayout_19">
                <item>
-                <widget class="FileSystemPathLineEdit" name="autoRun_txt" native="true"/>
+                <widget class="QLineEdit" name="autoRun_txt"/>
                </item>
                <item>
                 <widget class="QLabel" name="autoRun_param">