[imgui][many ports] Update to 1.92.6, support WebGPU feature

[luncliff]

Changes

Use https://github.com/ocornut/imgui/releases/tag/v1.92.5 for imgui port.
Use https://github.com/ocornut/imgui/releases/tag/v1.92.6 for imgui port.

I'm recently trying to use WebGPU feature of the imgui 1.92.5 with GLFW.
Add webgpu-binding feature with dawn dependency.

• Resolve [imgui] Add support for Dear ImGui WebGPU backend #44625 📍
• Resolve [imgui] update to 1.92.0 #46212 with higher minor version
• Resolve [imgui] update to 1.92.1 #46386 with higher minor version
• Resolve [imgui] update to v1.92.0 #46423 with higher minor version
• Conflicts [imgui] update to 1.92.1 #46495 🚧
• Conflicts [imgui] Update to 1.92.3 #47440 🚧
• Conflicts [imgui] update to 1.92.5 #48483 🚧

# Installs `imgui_impl_wgpu.h` header file
vcpkg install "imgui[webgpu-binding]"

Possible port usage example?

Maybe the test port vcpkg-ci-imgui?

• https://github.com/ocornut/imgui/blob/v1.92.5/examples/example_glfw_wgpu/main.cpp
• https://github.com/microsoft/vcpkg/blob/master/scripts/test_ports/vcpkg-ci-imgui/portfile.cmake
• [imgui] Add test-engine feature #38758

vcpkg install --overlay-ports "scripts/test_ports" "vcpkg-ci-imgui"

Notable API changes in ImGui

• https://github.com/ocornut/imgui/blob/v1.92.5/imgui.h#L3156
• https://github.com/ocornut/imgui/blob/v1.92.5/imgui.h#L3515
• https://github.com/ocornut/imgui/blob/v1.92.5/imgui.h#L3770-L3772
• https://github.com/ocornut/imgui/blob/v1.92.5/imgui.h#L3824

Port Changes

• imgui-sfml: feat: support for 1.92.0 SFML/imgui-sfml#330
• Overlay: update imgui to 1.92 OGRECave/ogre#3398
• 🚧 ...

Checklist

• Changes comply with the maintainer guide.
• SHA512s are updated for each updated download.
• The "supports" clause reflects platforms that may be fixed by this new version.
• Any fixed CI baseline entries are removed from that file.
• Any patches that are no longer applied are deleted from the port's directory.
• The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• Only one version is added to each modified port's versions file.