docs: Add comprehensive Vulkan testing guides for PR #2243

Add detailed testing documentation to help reviewers and contributors
test the Vulkan unit test framework locally.

Files added:
- VULKAN_TESTING_GUIDE.md: Comprehensive guide with installation
  instructions for macOS, Linux, and Windows, build configuration,
  troubleshooting, and platform-specific notes
- QUICK_TEST_STEPS.md: Quick reference guide with fast-track
  installation and testing steps for each platform

These guides address the request from @doug-walker to provide
instructions for installing Vulkan SDK and glslang dependencies
needed to test the Vulkan branch locally.

Signed-off-by: pmady <pavan4devops@gmail.com>

Author: pmady

QUICK_TEST_STEPS.md

@@ -0,0 +1,139 @@
+# Quick Testing Steps for PR #2243
+
+Hi @doug-walker! Here are the quick steps to test the Vulkan branch:
+
+## Quick Start (macOS)
+
+```bash
+# 1. Install dependencies
+brew install vulkan-sdk glslang
+
+# 2. Set environment variables
+export VULKAN_SDK=/usr/local/share/vulkan
+export PATH=$VULKAN_SDK/bin:$PATH
+export VK_ICD_FILENAMES=$VULKAN_SDK/share/vulkan/icd.d/MoltenVK_icd.json
+
+# 3. Verify installation
+vulkaninfo --summary
+glslangValidator --version
+
+# 4. Clone and build
+git clone https://github.com/AcademySoftwareFoundation/OpenColorIO.git
+cd OpenColorIO
+git remote add pmady https://github.com/pmady/OpenColorIO.git
+git fetch pmady
+git checkout pmady/vulkan-unit-tests
+
+mkdir build && cd build
+cmake .. \
+    -DCMAKE_BUILD_TYPE=Release \
+    -DOCIO_BUILD_TESTS=ON \
+    -DOCIO_VULKAN_ENABLED=ON \
+    -Dglslang_DIR=/usr/local/lib/cmake/glslang
+
+cmake --build . -j$(sysctl -n hw.ncpu)
+
+# 5. Run tests
+./tests/gpu/ocio_gpu_test --vulkan
+```
+
+## Quick Start (Linux - Ubuntu/Debian)
+
+```bash
+# 1. Install dependencies
+sudo apt-get update
+sudo apt-get install -y vulkan-tools libvulkan-dev vulkan-validationlayers \
+    glslang-tools libglslang-dev mesa-vulkan-drivers
+
+# 2. Verify installation
+vulkaninfo --summary
+glslangValidator --version
+
+# 3. Clone and build
+git clone https://github.com/AcademySoftwareFoundation/OpenColorIO.git
+cd OpenColorIO
+git remote add pmady https://github.com/pmady/OpenColorIO.git
+git fetch pmady
+git checkout pmady/vulkan-unit-tests
+
+mkdir build && cd build
+cmake .. \
+    -DCMAKE_BUILD_TYPE=Release \
+    -DOCIO_BUILD_TESTS=ON \
+    -DOCIO_VULKAN_ENABLED=ON
+
+cmake --build . -j$(nproc)
+
+# 4. Run tests
+./tests/gpu/ocio_gpu_test --vulkan
+```
+
+## Quick Start (Windows)
+
+```powershell
+# 1. Download and install Vulkan SDK from:
+# https://vulkan.lunarg.com/sdk/home#windows
+
+# 2. Verify installation (in PowerShell)
+vulkaninfo --summary
+glslangValidator --version
+
+# 3. Clone and build
+git clone https://github.com/AcademySoftwareFoundation/OpenColorIO.git
+cd OpenColorIO
+git remote add pmady https://github.com/pmady/OpenColorIO.git
+git fetch pmady
+git checkout pmady/vulkan-unit-tests
+
+mkdir build
+cd build
+cmake .. -G "Visual Studio 17 2022" -DCMAKE_BUILD_TYPE=Release -DOCIO_BUILD_TESTS=ON -DOCIO_VULKAN_ENABLED=ON
+cmake --build . --config Release
+
+# 4. Run tests
+.\tests\gpu\Release\ocio_gpu_test.exe --vulkan
+```
+
+## Common Issues
+
+**CMake can't find glslang:**
+```bash
+# Find glslang location
+find /usr -name "glslangConfig.cmake" 2>/dev/null
+
+# Add to cmake command:
+cmake .. -Dglslang_DIR=/path/to/glslang/lib/cmake/glslang ...
+```
+
+**No Vulkan device found:**
+```bash
+# Check Vulkan installation
+vulkaninfo
+
+# On Linux, install GPU drivers:
+sudo apt-get install mesa-vulkan-drivers  # For Intel/AMD
+# Or install NVIDIA/AMD proprietary drivers
+```
+
+**Tests crash:**
+```bash
+# Enable validation layers for debugging
+export VK_INSTANCE_LAYERS=VK_LAYER_KHRONOS_validation
+./tests/gpu/ocio_gpu_test --vulkan
+```
+
+## Expected Output
+
+```
+[==========] Running tests...
+[----------] Tests from GPURenderer
+[ RUN      ] GPURenderer.simple_transform
+Vulkan device: <Your GPU Name>
+[       OK ] GPURenderer.simple_transform
+...
+[  PASSED  ] All tests
+```
+
+For detailed instructions, see the full [VULKAN_TESTING_GUIDE.md](./VULKAN_TESTING_GUIDE.md).
+
+Let me know if you run into any issues!