[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/utility/report_utils.cpp

@@ -1,5 +1,6 @@
 #include "report_utils.h"
 
+#include "../../theme_manager.h"
 #include "libcockatrice/protocol/pb/serverinfo_report.pb.h"
 
 #include <QApplication>
@@ -7,6 +8,7 @@
 #include <QChar>
 #include <QColor>
 #include <QDateTime>
+#include <QFontDatabase>
 #include <QPalette>
 #include <QSharedPointer>
 #include <QTableWidget>
@@ -19,6 +21,20 @@
 namespace report_utils
 {
 
+QFont reportLogFont()
+{
+    if (themeManager->hasAppFont(AppFont::ChatLog)) {
+        return themeManager->appFont(AppFont::ChatLog);
+    }
+    QFont monoFont(QStringLiteral("monospace"));
+    monoFont.setStyleHint(QFont::Monospace);
+    const int systemPointSize = QFontDatabase::systemFont(QFontDatabase::GeneralFont).pointSize();
+    if (systemPointSize > 0) {
+        monoFont.setPointSize(systemPointSize);
+    }
+    return monoFont;
+}
+
 namespace
 {
 QColor reportStatusColor(const QString &status)