ui: Status bars dock button becomes dock/undock button

For people not used to the Yuzu UI it's not always clear if the emulated
console is docked or not.  The other items update their text when clicked,
this PR brings the DOCK button in line with this.

DOCK -> DOCKED or HANDHELD

src/yuzu/main.h

@@ -320,6 +320,7 @@ private:
     void MigrateConfigFiles();
     void UpdateWindowTitle(std::string_view title_name = {}, std::string_view title_version = {},
                            std::string_view gpu_vendor = {});
+    void UpdateDockedButton();
     void UpdateFilterText();
     void UpdateAAText();
     void UpdateStatusBar();