Fix "Add torrent dialog" spill-over on smaller screens

Done by adding an QScrollArea to the layout.

Closes #17387.

src/gui/addnewtorrentdialog.ui

@@ -11,6 +11,39 @@
    </rect>
   </property>
   <layout class="QVBoxLayout" name="AddNewTorrentDialogLayout">
+   <item>
+    <widget class="QScrollArea" name="scrollArea_2">
+     <property name="frameShape">
+      <enum>QFrame::NoFrame</enum>
+     </property>
+     <property name="sizeAdjustPolicy">
+      <enum>QAbstractScrollArea::AdjustToContents</enum>
+     </property>
+     <property name="widgetResizable">
+      <bool>true</bool>
+     </property>
+     <widget class="QWidget" name="scrollAreaWidgetContents_2">
+      <property name="geometry">
+       <rect>
+        <x>0</x>
+        <y>0</y>
+        <width>868</width>
+        <height>644</height>
+       </rect>
+      </property>
+      <layout class="QVBoxLayout" name="verticalLayout_6">
+       <property name="leftMargin">
+        <number>0</number>
+       </property>
+       <property name="topMargin">
+        <number>0</number>
+       </property>
+       <property name="rightMargin">
+        <number>0</number>
+       </property>
+       <property name="bottomMargin">
+        <number>0</number>
+       </property>
        <item>
         <widget class="QSplitter" name="splitter">
          <property name="orientation">
@@ -302,10 +335,21 @@
                 <property name="frameShape">
                  <enum>QFrame::NoFrame</enum>
                 </property>
+                <property name="sizeAdjustPolicy">
+                 <enum>QAbstractScrollArea::AdjustToContents</enum>
+                </property>
                 <property name="widgetResizable">
                  <bool>true</bool>
                 </property>
                 <widget class="QWidget" name="scrollAreaWidgetContents">
+                 <property name="geometry">
+                  <rect>
+                   <x>0</x>
+                   <y>0</y>
+                   <width>392</width>
+                   <height>68</height>
+                  </rect>
+                 </property>
                  <layout class="QVBoxLayout" name="verticalLayout_2">
                   <property name="leftMargin">
                    <number>0</number>
@@ -415,9 +459,6 @@
                <property name="orientation">
                 <enum>Qt::Horizontal</enum>
                </property>
-           <property name="sizeType">
-            <enum>QSizePolicy::Maximum</enum>
-           </property>
                <property name="sizeHint" stdset="0">
                 <size>
                  <width>165</width>
@@ -451,6 +492,10 @@
          </widget>
         </widget>
        </item>
+      </layout>
+     </widget>
+    </widget>
+   </item>
    <item>
     <layout class="QHBoxLayout" name="buttonsHLayout">
      <item>