migration from nvpro_core to pknowles/vulkan_objects

[pknowles]

Mostly non-functional refactor, replacing nvpro_core with vulkan_objects

This commit ports the entire application to the modern vulkan_objects
stack, removing many nvpro_core utilities and ecosystem dependencies in
favor of explicit, RAII-based Vulkan primitives, layered utilities and
features with clearer separation of concerns.

Core architecture changes

• Replaced nvvkhl::Application with layered utilities
• The main loop is visible in main() using e.g.
  vko::simple::Swapchain and vko::glfw::*
• Vulkan SDK dependency removed, now handled by vulkan_objects
• No global Vulkan symbols/functions

Memory, buffers, and images

• Replaced nvvk::ResourceAllocator, MemAllocator, and
  StagingMemoryManager
• Now using vko::vma::Allocator + vko::StagingStream
• Buffers migrated to vko::DeviceBuffer / vko::BoundBuffer
• Images/textures migrated to vko::BoundImage and vko::ViewedImage
• Staging via vko::upload() and vko::download()

Pipelines, descriptors, and ray tracing

• Replaced nvvk::DescriptorSetContainer with:
  vko::BindingsAndFlags, vko::SingleDescriptorSet,
  vko::WriteDescriptorSetBuilder

• Graphics, compute, and ray tracing pipelines rebuilt using vko
  RAII wrappers

• Shader Binding Tables migrated to vko::simple::ShaderBindingTables

• Existing ray tracing acceleration structure utilities ported to use
  vko helpers

Command buffers, queues, and synchronization

• Most visible vulkan calls are now vkCmd*, which are on the
  vko::Device function table
• Timeline semaphore based submission via vko queue wrapper,
  which adds the concept of an explicit submit promise
• New memory barrier and debug label calls

UI, tooling, and utilities

• Direct ImGui + ImPlot integration (no nvvkhl elements)
• Just using std::print() instead of LOGE etc.
• Command-line parsing with Taywee/args
• File utilities replaced with std::filesystem

Legacy isolation

• Introduced nvpro_core_legacy_static for unavoidable leftovers:
• DDS/KTX texture loading
• Tonemapper postprocess
• ImGui icon font

Build & tooling

• CMake mostly using FetchContent
• Removed nvpro_core build logic and custom macros
• Vulkan SDK no longer required