chore: Cleanup REUSE implementation

[KhronosWebservices]

• cleanup REUSE.toml - fix one incorrect copyright assignment
• add GitHub reuse Action workflow
• add LICENSE.txt

Currently for the following files I have set Khronos Group as the copyright holder. I am unsure if this is correct. Before merging, can this be verified?

    "layers/vk_layer_settings.txt",
    "layers/libVkLayer_khronos_timeline_semaphore.map",
    "layers/libVkLayer_khronos_synchronization2.map",
    "layers/libVkLayer_khronos_memory_decompression.map",
    "layers/libVkLayer_khronos_shader_object.map",
    "layers/json/VkLayer_khronos_memory_decompression.json.in",
    "layers/json/VkLayer_khronos_synchronization2.json.in",
    "layers/json/VkLayer_khronos_shader_object.json.in",
    "layers/json/VkLayer_khronos_timeline_semaphore.json.in",
    "layers/shader_object/generated/.clang-format",

[ci-tester-lunarg]

Author KhronosWebservices not on autobuild list. Waiting for curator authorization before starting CI build.

[ci-tester-lunarg]

CI Vulkan-ExtensionLayer build queued with queue ID 741084.

[ci-tester-lunarg]

CI Vulkan-ExtensionLayer build # 1121 running.

[charles-lunarg]

@jeremyg-lunarg @ziga-lunarg Can you help decide who the copyright for those files belong to? I believe they should belong to whoever originally created the layer. (the .map and .in files). The vk_layer_settings.txt and .clang-format are likely lunarg's in the course of repo maintenance, but I am not sure.

[ziga-lunarg]

@jeremyg-lunarg @ziga-lunarg Can you help decide who the copyright for those files belong to? I believe they should belong to whoever originally created the layer. (the .map and .in files). The vk_layer_settings.txt and .clang-format are likely lunarg's in the course of repo maintenance, but I am not sure.

Shader object files should be Nintendo

[ci-tester-lunarg]

CI Vulkan-ExtensionLayer build # 1121 passed.

[KhronosWebservices]

Each libVkLayer was uploaded by a different person. Unless otherwise noted, I will assign copyright to that company and push an update to this PR later today

[KhronosWebservices]

@charles-lunarg @ziga-lunarg Before I push a fix for the above, technically, a lot of files currently copyright LunarG were originally submitted by Samsung. Any objection that I add copyright for those files to be Samsung/LunarG/Khronos?

[KarenGhavam-lunarG]

Any objection that I add copyright for those files to be Samsung/LunarG/Khronos?

No objections from LunarG

[ci-tester-lunarg]

Author KhronosWebservices not on autobuild list. Waiting for curator authorization before starting CI build.

[KhronosWebservices]

Ended up with Khronos/LunarG as that is what the other files had that were uploaded by the same user.