Add support building llvmlite wheels for Windows ARM64

[MugundanMCW]

PR Description:

As discussed in numba/llvmlite#1387 (comment), this PR introduces support for building llvmlite wheels on Windows ARM64.

Changes proposed:

• Created CI workflow[llvmlite_win-arm64_wheel_builder.yml] for building llvmlite wheels on Windows ARM64.
• Created build script[bld_llvm_winarm64.bat] for compiling llvm on Windows ARM64.
• Added patch to modify ffi/build.py to detect the target platform based upon the system architecture.

[khmyznikov]

@MugundanMCW let's make folder llvmlite under workflows and put there all scripts except main one which builds the actual wheel, that one need to put alongside the others llvmlite_wheel.yml

[MugundanMCW]

Hi @khmyznikov,
Thanks for the suggestion. I have moved the build scripts into the llvmlite folder under .github/workflows as requested.
Let me know if anything else needs to be updated.