Enhance Support for Reading and Writing Metal Libraries

- fully support metallib v2.7: RFLT, reflection list
- fix UUID computation to be based on the module's data
- figure out which LLVM IR version AIR v2.5 corresponds to

### See also:
- https://github.com/YuAo/MetalLibraryArchive
- floor library
- https://github.com/a2flo/floor_llvm/blob/floor_toolchain_1406/llvm/lib/Bitcode/MetalLib/MetalLibWriterPass.cpp
- https://github.com/a2flo/floor_llvm/blob/floor_toolchain_1406/llvm/tools/metallib-dis/metallib-dis.cpp

### Relevant `TODO`:

https://github.com/JuliaGPU/Metal.jl/blob/6a760a60a33b864b2c7fa3e856e38e1e6299f871/src/compiler/library.jl#L1-L12