Imgui sdl3 bindings

[constcuriosity]

Adds new sdl3-binding and sdl3-renderer-binding features to the imgui port.

Imgui already has backends implemented for sdl3. They just hadn't yet been exposed as options like the sdl2 backends were. This change mainly just copies the same operations that are done for sdl2 support, but swaps the 2 for a 3.

• 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.

[constcuriosity]

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