[Client] Add option to use game time in game log timestamps (#7265)

* [Client] Add option to use game time in game log timestamps (#2202)

Game log timestamps showed the local clock time, which is meaningless in
a replay or in a log read after the fact — nobody can tell when a play
happened relative to the game.

Add a "Use game time instead of local time in game logs" setting. When
enabled, the message log stamps entries with the elapsed game time
(HH:MM:SS since the game started); regular chat views keep the local
clock.

* [Game] Move formatElapsedTime helper out of public slots (#2202)

The message log needs the HH:MM:SS formatter used by the game timer, but
it lives in GameState's public slots, tying a pure formatting helper to
the signal-slot machinery.

Move formatElapsedTime into a public section of GameState so the log can
call it directly, and add the missing trailing newline to game_state.cpp.

---------

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>

libcockatrice_interfaces/libcockatrice/interfaces/interface_chat_settings_provider.h

@@ -21,6 +21,7 @@ public:
     [[nodiscard]] virtual bool getShowMentionPopup() const = 0;
     [[nodiscard]] virtual bool getRoomHistory() const = 0;
     [[nodiscard]] virtual bool getIgnoreAllPrivateMessages() const = 0;
+    [[nodiscard]] virtual bool getUseGameTime() const = 0;
     [[nodiscard]] virtual QString getHighlightWords() const = 0;
 };