Remove the upgrade reminder

We haven't activated it for a long time, and nowadays PPSSPP has a completely
different level of compatibility and performance compared to back when
we added the upgrade reminder.

Also I'm no longer a fan of HTTP requests on startup, even if only every
10 times like we did.

So, away it goes.

Moved the potentially useful translation strings into [Dialog].

UI/RemoteISOScreen.cpp

@@ -636,6 +636,4 @@ void RemoteISOBrowseScreen::CreateViews() {
 	}
 
 	root_->SetDefaultFocusView(tabHolder_);
-
-	upgradeBar_ = 0;
 }