b8056

cmake : fix KleidiAI install target failure with EXCLUDE_FROM_ALL (#19581)

• cmake: fix KleidiAI install target failure with EXCLUDE_FROM_ALL

Fix for the bug #19501 by adding EXCLUDE_FROM_ALL to FetchContent_Declare. This properly excludes KleidiAI from both build and install targets, preventing install failures when GGML_CPU_KLEIDIAI=ON is used.

The KleidiAI source files are still compiled into libggml-cpu.so, preserving all functionality.

• addressed code review comments

macOS/iOS:

• macOS Apple Silicon (arm64)
• macOS Intel (x64)
• iOS XCFramework

Linux:

• Ubuntu x64 (CPU)
• Ubuntu x64 (Vulkan)
• Ubuntu s390x (CPU)

Windows:

• Windows x64 (CPU)
• Windows arm64 (CPU)
• Windows x64 (CUDA 12) - CUDA 12.4 DLLs
• Windows x64 (CUDA 13) - CUDA 13.1 DLLs
• Windows x64 (Vulkan)
• Windows x64 (SYCL)
• Windows x64 (HIP)

openEuler:

• openEuler x86 (310p)
• openEuler x86 (910b, ACL Graph)
• openEuler aarch64 (310p)
• openEuler aarch64 (910b, ACL Graph)