Add Auto CPU/GPU sync mode (renderer low latency)

[darksylinc]

Add CPU_GPU_SYNC_AUTO
Remove redundant calls to get_ticks_usec()

Fixes an unrelated bug when NAVIGATION_2D_DISABLED or NAVIGATION_3D_DISABLED are defined.

This is a modified version of #100031

Notable changes:

1. Forbids the use of CPU_GPU_SYNC_SEQUENTIAL in production. It is allowed in the Editor, as it has its uses for debugging tight timing issues.
2. Adds CPU_GPU_SYNC_AUTO which decides on realtime whether to use SEQUENTIAL or PARALLEL.
   • AUTO is disabled on OpenGL. The timing was too unreliable and every time it switched between SEQ and PAR a very visible stutter would occur.
   • AUTO has been tested by me on:
     • Vulkan Linux AMD (Mesa RADV)
     • Vulkan Windows AMD
     • Vulkan Windows NVIDIA
     • D3D12 Windows AMD
     • D3D12 Windows NVIDIA
3. Refactors the code as it lives in RenderingServer, since frame pacing is irrespective of implementation. It addresses the problems found in this comment. Frame Pacing code is a bit odd, because it involves very low level mechanisms (e.g. synchronization) but it needs to be aware of the engine as a whole at a very high level (in fact changes, albeit small, go all way to main.cpp).
4. Adds monitors to debug and understand by AUTO decides to use SEQ or PAR.
   • Those monitors are very useful even outside of frame pacing. They are very sensible to frame spikes and can detect issues that would cause stutter problems (even outside of AUTO/SEQ/PAR; as any frame time spike or hard missed target is very bad)

This is how the Monitors look like on a simple project, V-Sync enabled:

[darksylinc]

Superseeded by #106221