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

bye bye nuuls

src/common/Common.hpp

@@ -5,17 +5,17 @@
 #include <QWidget>
 
 #include <memory>
-#include <optional>
-#include <string>
-
-#define LINK_CHATTERINO_WIKI "https://wiki.chatterino.com"
-#define LINK_CHATTERINO_DISCORD "https://discord.gg/7Y5AYhAK4z"
-#define LINK_CHATTERINO_SOURCE "https://github.com/Chatterino/chatterino2"
 
 namespace chatterino {
 
-const inline auto TWITCH_PLAYER_URL =
-    QStringLiteral("https://player.twitch.tv/?channel=%1&parent=twitch.tv");
+constexpr QStringView LINK_CHATTERINO_WIKI = u"https://wiki.chatterino.com";
+constexpr QStringView LINK_CHATTERINO_DISCORD =
+    u"https://discord.gg/7Y5AYhAK4z";
+constexpr QStringView LINK_CHATTERINO_SOURCE =
+    u"https://github.com/Chatterino/chatterino2";
+
+constexpr QStringView TWITCH_PLAYER_URL =
+    u"https://player.twitch.tv/?channel=%1&parent=twitch.tv";
 
 enum class HighlightState {
     None,
@@ -23,21 +23,14 @@ enum class HighlightState {
     NewMessage,
 };
 
-const Qt::KeyboardModifiers showSplitOverlayModifiers =
+constexpr Qt::KeyboardModifiers SHOW_SPLIT_OVERLAY_MODIFIERS =
     Qt::ControlModifier | Qt::AltModifier;
-const Qt::KeyboardModifiers showAddSplitRegions =
+constexpr Qt::KeyboardModifiers SHOW_ADD_SPLIT_REGIONS =
     Qt::ControlModifier | Qt::AltModifier;
-const Qt::KeyboardModifiers showResizeHandlesModifiers = Qt::ControlModifier;
+constexpr Qt::KeyboardModifiers SHOW_RESIZE_HANDLES_MODIFIERS =
+    Qt::ControlModifier;
 
-#ifndef ATTR_UNUSED
-#    ifdef Q_OS_WIN
-#        define ATTR_UNUSED
-#    else
-#        define ATTR_UNUSED __attribute__((unused))
-#    endif
-#endif
-
-static const char *ANONYMOUS_USERNAME_LABEL ATTR_UNUSED = " - anonymous - ";
+constexpr const char *ANONYMOUS_USERNAME_LABEL = " - anonymous - ";
 
 template <typename T>
 std::weak_ptr<T> weakOf(T *element)