chore: remove Singleton & replace getIApp with getApp (#5514)

benchmarks/src/RecentMessages.cpp

@@ -2,8 +2,8 @@
 #include "controllers/accounts/AccountController.hpp"
 #include "controllers/highlights/HighlightController.hpp"
 #include "messages/Emote.hpp"
+#include "mocks/BaseApplication.hpp"
 #include "mocks/DisabledStreamerMode.hpp"
-#include "mocks/EmptyApplication.hpp"
 #include "mocks/LinkResolver.hpp"
 #include "mocks/TwitchIrcServer.hpp"
 #include "mocks/UserData.hpp"
@@ -32,9 +32,14 @@ using namespace literals;
 
 namespace {
 
-class MockApplication : mock::EmptyApplication
+class MockApplication : public mock::BaseApplication
 {
 public:
+    MockApplication()
+        : highlights(this->settings, &this->accounts)
+    {
+    }
+
     IEmotes *getEmotes() override
     {
         return &this->emotes;