fix: replace defines with constexpr/const and use more absolute paths for includes (#5527)

bye bye nuuls

src/widgets/dialogs/SelectChannelDialog.cpp

@@ -1,4 +1,4 @@
-#include "SelectChannelDialog.hpp"
+#include "widgets/dialogs/SelectChannelDialog.hpp"
 
 #include "Application.hpp"
 #include "common/QLogging.hpp"
@@ -25,11 +25,11 @@
 #include <QTableView>
 #include <QVBoxLayout>
 
-#define TAB_TWITCH 0
-#define TAB_IRC 1
-
 namespace chatterino {
 
+constexpr int TAB_TWITCH = 0;
+constexpr int TAB_IRC = 1;
+
 SelectChannelDialog::SelectChannelDialog(QWidget *parent)
     : BaseWindow(
           {