Add controller input and a laser-pointer-driven menu quad

- xr_input.c/h: an OpenXR action set (aim pose, trigger/select click, a
  menu-toggle button) plus ray/quad hit-testing, and a visible
  laser-pointer line drawn from the controller toward the hit point.
- xr_menu.c/h + MenuOverlay.java: a second composition-layer quad,
  toggled by a controller button, showing an off-screen, never-attached
  Android View tree (one "Keyboard" button so far) driven by synthetic
  touch events computed from the laser ray's hit UV.
- Migrate gl4es from a prebuilt binary baked into the Docker build-image
  to a vendored source snapshot (android/gl4es-src/) compiled from
  source at APK build time via CMake add_subdirectory(), patched through
  a new android/gl4es-patches/ (mirrors the existing engine-patches/
  pattern). This was needed to track down and fix a bug hit while
  building the menu: gl4es's fixed-pipeline emulation (fpe.c) was
  unconditionally substituting its own shader onto the menu's draw call
  (fpe_ReleventState() always sets alphafunc to a nonzero sentinel, so
  its fpe_IsEmpty() check could never see the state as empty), making
  the menu quad show the game's own rendering instead of its own
  content. Fixed by routing the menu's blit through a real
  glBlitFramebuffer() call instead of a shader-based draw, which gl4es's
  fpe.c has nothing to intercept - documented in README.md's new
  "Debugging notes" section.
- Renumber android/engine-patches/ to close the gap left by removing an
  unrelated diagnostic-only patch, and strip investigation-journal
  comments and dead diagnostic code (temporary tracing, env-var probes)
  left over from finding the bug above.
- Restructure README.md into numbered sections, document every
  engine/gl4es patch, add Android Studio dev/testing-cycle instructions,
  and generalize Quest-specific wording to any OpenXR headset. Update
  NOTICE.txt to match (gl4es is now vendored/patched source, not a
  prebuilt binary; add the OpenXR-SDK loader).

android/gl4es-src/test.cmake

@@ -0,0 +1,62 @@
+# Check if all required arguments are provided
+macro(argument_required argument failstring)
+	if (NOT ${argument})
+		message(FATAL_ERROR ${failstring})
+	endif (NOT ${argument})
+endmacro(argument_required)
+
+argument_required(LIBRARY_FOLDER "All tests require to have a library output folder.")
+argument_required(TESTS_DIRECTORY "All tests require to have a test folder.")
+argument_required(TEST_FILENAME "All tests require a trace filename to be reprinted.")
+argument_required(CALLS "All tests require a call count.")
+
+# Enable different GLES version tests
+if (GLES_FORCED)
+	set(GLES${GLES_FORCED}_ENABLED ON)
+else (GLES_FORCED)
+	set(GLES1_ENABLED ON)
+	set(GLES2_ENABLED ON)
+endif (GLES_FORCED)
+
+# Special case fo pixels tolerance
+if (TOLERANCE)
+	set(TOLERANCE_GLES1 ${TOLERANCE})
+	set(TOLERANCE_GLES2 ${TOLERANCE})
+endif (TOLERANCE)
+
+# Use the built library
+set(ENV{LD_LIBRARY_PATH} ${LIBRARY_FOLDER}:$ENV{LD_LIBRARY_PATH})
+
+macro(run_test GLES)
+	if (GLES${GLES}_ENABLED)
+		argument_required(TOLERANCE_GLES${GLES} "All tests require a pixel tolerance for GLES ${GLES}.")
+
+		set(ENV{LIBGL_ES} ${GLES})
+
+		message(STATUS "Starting test in GLES ${GLES}...")
+		execute_process(
+			COMMAND ${TESTS_DIRECTORY}/test.sh
+			${TEST_FILENAME}
+			${CALLS}
+			${TOLERANCE_GLES${GLES}}
+			${EXTRACT_RANGE}
+			ERROR_VARIABLE TEST_ERROR
+			OUTPUT_VARIABLE TEST_OUTPUT
+			WORKING_DIRECTORY ${TESTS_DIRECTORY}
+		)
+		message(STATUS "Ran test.\nError: ${TEST_ERROR}\nOutput: ${TEST_OUTPUT}")
+		
+		if (TEST_OUTPUT)
+			set(ERROR ${ERROR} ${GLES})
+		endif (TEST_OUTPUT)
+	endif (GLES${GLES}_ENABLED)
+endmacro(run_test)
+
+run_test(1)
+run_test(2)
+
+if (ERROR)
+	message(FATAL_ERROR "Test(s) failed while using GLES ${ERROR}")
+endif (ERROR)
+
+message(STATUS "Success.")