[WebAssembly] Implement all f16x8 binary instructions. (#93360)

This reuses most of the code that was created for f32x4 and f64x2 binary
instructions and tries to follow how they were implemented.

add/sub/mul/div - use regular LL instructions
min/max - use the minimum/maximum intrinsic, and also have builtins
pmin/pmax - use the wasm.pmax/pmin intrinsics and also have builtins

Specified at:

https://github.com/WebAssembly/half-precision/blob/29a9b9462c9285d4ccc1a5dc39214ddfd1892658/proposals/half-precision/Overview.md