[clang] [llvm] [WebAssembly] Change half-precision feature name to fp16. (PR #105434)

[Heejin Ahn via cfe-commits]

https://github.com/aheejin commented:

I know it is a little pedantic, but I recently sorted the features alphabetically (#90777)... Can you move the new `fp16` entries so that the lists are alphabetically sorted in the files?

https://github.com/llvm/llvm-project/pull/105434