atmosphere: extract API version management to common folder

stratosphere/pm/source/pm_main.cpp

@@ -94,12 +94,7 @@ void __appInit(void) {
         fatalSimple(0xCAFE << 4 | 6);
     }
     
-    /* Check for exosphere API compatibility. */
-    u64 exosphere_cfg;
-    if (R_FAILED(splGetConfig((SplConfigItem)65000, &exosphere_cfg))) {
-        fatalSimple(0xCAFE << 4 | 0xFF);
-        /* TODO: Does PM need to know about target firmware/master key revision? If so, extract from exosphere_cfg. */
-    }
+    CheckAtmosphereVersion();
 }
 
 void __appExit(void) {