Android: Require user to enable savestate menus

With the nature of android updates invalidating save states, it's best to hide
these options unless enabled by the user. The option to use savestates can now
be enabled via the General settings menu.

Source/Android/app/src/main/res/values/strings.xml

@@ -135,6 +135,8 @@
     <string name="wiimote_speaker_description">Enable sound output through the speaker on a real Wiimote (DolphinBar required).</string>
     <string name="audio_stretch">Audio Stretching</string>
     <string name="audio_stretch_description">Stretches audio to reduce stuttering. Increases latency.</string>
+    <string name="enable_save_states">Enable Savestates</string>
+    <string name="enable_save_states_description">WARNING: Savestates may not be compatible with future versions of Dolphin and can make it impossible to create normal saves in some cases. Never use savestates as the only way of saving your progress.</string>
     <string name="analytics">Enable usage statistics reporting</string>
     <string name="analytics_desc">If authorized, Dolphin can collect data on its performance, feature usage, and configuration, as well as data on your system\'s hardware and operating system.\n\nNo private data is ever collected. This data helps us understand how people and emulated games use Dolphin and prioritize our efforts. It also helps us identify rare configurations that are causing bugs, performance and stability issues. This authorization can be revoked at any time through Dolphin\'s settings.</string>
     <string name="gametdb_thanks">Thanks to GameTDB.com for providing GameCube and Wii covers!</string>