core: settings: Add setting for debug assertions and disable by default.

- This is a developer-only setting and no longer needs to be enabled by default.
- Also adds "use_auto_stub" setting to SDL frontend while we are here.
- Supersedes #1340.

src/yuzu/configuration/configure_debug.ui

@@ -185,6 +185,13 @@
         </property>
        </widget>
       </item>
+       <item>
+         <widget class="QCheckBox" name="use_debug_asserts">
+           <property name="text">
+             <string>Enable Debug Asserts</string>
+           </property>
+         </widget>
+       </item>
        <item>
          <widget class="QCheckBox" name="use_auto_stub">
            <property name="text">