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/core/core.cpp

@@ -379,7 +379,8 @@ System::ResultStatus System::Init(Frontend::EmuWindow& emu_window,
 
     memory = std::make_unique<Memory::MemorySystem>(*this);
 
-    timing = std::make_unique<Timing>(num_cores, Settings::values.cpu_clock_percentage.GetValue());
+    timing = std::make_unique<Timing>(num_cores, Settings::values.cpu_clock_percentage.GetValue(),
+                                      movie.GetOverrideBaseTicks());
 
     kernel = std::make_unique<Kernel::KernelSystem>(
         *memory, *timing, [this] { PrepareReschedule(); }, memory_mode, num_cores, n3ds_hw_caps,