[WebAssembly] Select lane stores for floating-point vectors (#219186)
This extends the existing integer vector lane-store patterns to the
equivalent floating-point vector types. The underlying WebAssembly
instructions are type-agnostic lane stores.
That being said I think something like `STORE_LANE_I32x4_A32` can be
misleading when dealing with floating-point vectors. (should there be a
rename or something ?)