[Fonts] Keep ChatView on the app font and share the report log font

- ChatLog's unset fallback is qApp->font() again: ChatView never set a font
  before the role existed, so an unset role must not switch chat and the game
  log to monospace at the system GeneralFont size.
- Move the monospace fallback the report dialogs used before into
  report_utils::reportLogFont(), which returns the theme's ChatLog role when it
  is set and the old monospace otherwise. tab_report, dlg_my_reports and
  dlg_report_user now share it, so they cannot drift and they honour a themed
  size instead of overriding it.

cockatrice/src/interface/widgets/dialogs/dlg_report_user.cpp

@@ -1,11 +1,13 @@
 #include "dlg_report_user.h"
 
 #include "../interface/theme_manager.h"
+#include "../utility/report_utils.h"
 #include "abstract_client.h"
 #include "libcockatrice/protocol/pb/response.pb.h"
 
 #include <QComboBox>
 #include <QDialogButtonBox>
+#include <QFont>
 #include <QGridLayout>
 #include <QGroupBox>
 #include <QLabel>
@@ -124,14 +126,7 @@ DlgReportUser::DlgReportUser(AbstractClient *_client,
 
 void DlgReportUser::applyChatLogFont()
 {
-    // Family comes from the ChatLog theme role; size stays caller-side as before.
-    QFont monoFont = themeManager->appFont(AppFont::ChatLog);
-    monoFont.setStyleHint(QFont::Monospace);
-    const int systemPointSize = QFontDatabase::systemFont(QFontDatabase::GeneralFont).pointSize();
-    if (systemPointSize > 0) {
-        monoFont.setPointSize(systemPointSize);
-    }
-    chatLogEdit->setFont(monoFont);
+    chatLogEdit->setFont(report_utils::reportLogFont());
 }
 
 void DlgReportUser::actSubmit()