Put externalPluginIsSet as its own global; initialize it at launch

src/main.c

@@ -51,6 +51,7 @@ cx_sha3_t global_sha3;
 uint8_t appState;
 bool dataPresent;
 bool called_from_swap;
+bool externalPluginIsSet;
 #ifdef HAVE_STARKWARE
 bool quantumSet;
 #endif
@@ -72,6 +73,7 @@ void reset_app_context() {
     // PRINTF("!!RESET_APP_CONTEXT\n");
     appState = APP_STATE_IDLE;
     called_from_swap = false;
+    externalPluginIsSet = false;
 #ifdef HAVE_STARKWARE
     quantumSet = false;
 #endif