Fix SPIRV-LLVM-Translator header file path in out-of-tree build

[wenju-he]

Changes:

• Upgrade Ubuntu version to 24.04
• Switch legacy 'apt-key add -' to /etc/apt/keyrings/llvm.gpg
• Prepend SPIRV-LLVM-Translator header file path with LLVMSPIRVLib

Resolves #646

[Copilot]

Pull request overview

This PR fixes out-of-tree builds against separately packaged LLVM + SPIRV-LLVM-Translator by adjusting SPIRV-LLVM-Translator include paths for the prebuilt-LLVM configuration, and updates CI workflows to use Ubuntu 24.04 and modern LLVM apt repository key handling.

Changes:

• Update options.h / options_compile.cpp to include SPIRV-LLVM-Translator headers from LLVMSPIRVLib/... when USE_PREBUILT_LLVM is defined.
• Update GitHub Actions workflows to run on Ubuntu 24.04 and replace deprecated apt-key usage with /etc/apt/keyrings/llvm.gpg.
• Fix workflow env var naming for SPIRV_TRANSLATOR_DIR by switching to an underscore-based variable name.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
options.h	Adjusts SPIRV-LLVM-Translator header include path for prebuilt-LLVM builds.
options_compile.cpp	Adjusts .inc include path for SPIRV extension table in prebuilt-LLVM builds.
.github/workflows/on-push-verification-out-of-tree.yml	Moves CI to ubuntu-24.04, updates LLVM apt key setup, and fixes env var naming.
.github/workflows/codeql.yml	Moves CodeQL job to ubuntu-24.04 and updates LLVM apt key setup and env var naming.

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