addpkg(x11/luanti{-common,-server}): 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](termux#22353) or [new virglrenderer](termux#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

- I made 6 patches, but the patch 0001-enable-egl-without-sdl2.patch is
  a cherry pick of minetest/minetest@4838eb2

x11-packages/luanti/0002-fix-elf-directory-for-cross-compiling.patch

@@ -0,0 +1,14 @@
+Luanti seems to not have previously been exposed to cross-compiling executables
+for platforms other than SurfaceFlinger. This prevents the error
+"CMake Error: failed to create symbolic link '/minetest': Permission denied"
+--- a/src/CMakeLists.txt
++++ b/src/CMakeLists.txt
+@@ -569,7 +569,7 @@ endif()
+
+ # When cross-compiling assume the user doesn't want to run the executable anyway,
+ # otherwise place it in <source dir>/bin/ since Luanti can only run from there.
+-if(NOT CMAKE_CROSSCOMPILING)
++if(NOT THIS_IS_FOR_SURFACEFLINGER_IN_OWOKITTYS_OPINION)
+ 	set(EXECUTABLE_OUTPUT_PATH "${CMAKE_SOURCE_DIR}/bin")
+ endif()
+