System: Add a new throttler/pacer which can catch up on lost time

This can result in worse frame pacing, so if you have a decent machine
you'll probably want to turn on "display all frames" in display
settings.

But, it's sadly needed for Android.

src/duckstation-qt/displaysettingswidget.ui

@@ -85,6 +85,13 @@
           </property>
          </widget>
         </item>
+        <item row="1" column="1">
+         <widget class="QCheckBox" name="displayAllFrames">
+          <property name="text">
+           <string>Display All Frames</string>
+          </property>
+         </widget>
+        </item>
        </layout>
       </item>
      </layout>
@@ -125,7 +132,7 @@
       </item>
       <item row="2" column="1">
        <widget class="QComboBox" name="gpuDownsampleMode"/>
-      </item>       
+      </item>
       <item row="3" column="0" colspan="2">
        <layout class="QGridLayout" name="gridLayout_2">
         <item row="0" column="0">