addpkg(x11/luanti): moved from TUR

Copied and pasted from https://github.com/termux-user-repository/tur/tree/master/tur/luanti

Previous documentation here:
- termux-user-repository/tur#1295
- termux-user-repository/tur#1296
- termux-user-repository/tur#1331
- termux-user-repository/tur#1327

Summary of key points:

- for better performance than normal virglrenderer-android, test using [termux-wsi-layer](#22353) or [new virglrenderer](#22385)

- to use touchscreen input, set "Touchscreen input mode: Direct touch" in Termux:X11 settings

- to use keyboard input, set "Prefer scancodes" in Termux:X11 settings

- to use mouse input, set "Capture external pointer devices" in
  Termux:X11 settings