core_timing: Allow configuring a fixed or random initial system tick value. (#7309)

* core_timing: Apply random base ticks value on startup.

* core: Maintain consistent base system ticks in TAS movies.

* frontend: Add setting to configure a fixed base system ticks value.

src/citra_qt/configuration/configure_system.h

@@ -43,6 +43,7 @@ private:
 
     void UpdateBirthdayComboBox(int birthmonth_index);
     void UpdateInitTime(int init_clock);
+    void UpdateInitTicks(int init_ticks_type);
     void RefreshConsoleID();
 
     void SetupPerGameUI();