Rapid auto fire & Changed default GPU

Support Rapid Auto-Fire (Windows, Linux, macOS)

Added shot firing function for keyboard input.
The c key is assigned by default.
It can be customized to any key with CTRL+K (Windows) or config.json (Linux/macOS).

bugfix: Keyboard configuration does not saved (Windows)

A bug in the Windows version that caused keyboard assignment settings to be reset to default settings after rebooting, has been addressed.

Changed default GPU (Linux)

The default GPU at startup has been changed from OpenGL to Vulkan.
In environments where Vulkan is not available, OpenGL is used as before.
In environments where OpenGL is not available, software rendering can be used by specifying the startup option: -g None

Changed default GPU (macOS)

The default GPU at startup has been changed from OpenGL to Metal.
On environments where Metal is not available, OpenGL is used as before.
On environments where OpenGL is not available, software rendering can be used by specifying the startup option: -g None