UI: Add file splitting option "Only split manually"

UI/data/locale/en-US.ini

@@ -990,6 +990,7 @@ Basic.Settings.Output.Adv.FFmpeg.Settings="FFmpeg Settings"
 Basic.Settings.Output.EnableSplitFile="Automatic File Splitting"
 Basic.Settings.Output.SplitFile.TypeTime="Split by Time"
 Basic.Settings.Output.SplitFile.TypeSize="Split by Size"
+Basic.Settings.Output.SplitFile.TypeManual="Only split manually"
 Basic.Settings.Output.SplitFile.Time="Split Time"
 Basic.Settings.Output.SplitFile.Size="Split Size"
 Basic.Settings.Output.SplitFile.ResetTimestamps="Reset timestamps at the beginning of each split file"

UI/forms/OBSBasicSettings.ui

@@ -2923,6 +2923,11 @@
                                    <string>Basic.Settings.Output.SplitFile.TypeSize</string>
                                   </property>
                                  </item>
+                                 <item>
+                                  <property name="text">
+                                   <string>Basic.Settings.Output.SplitFile.TypeManual</string>
+                                  </property>
+                                 </item>
                                 </widget>
                                </item>
                                <item row="8" column="0">