andnot: Wasm SIMD bitwise instruction

Try it

(module
  (import "console" "log" (func $log (param i32)))
  (func $main
    v128.const i16x8 10 23 56 15 25 29 92 45
    v128.const i16x8 12 42 58 25 55 91 192 4
    v128.andnot

    i8x16.extract_lane_u 6
    call $log ;; log the result
  )
  (start $main)
)

WebAssembly.instantiateStreaming(fetch("{%wasm-url%}"), { console });

In the above example, the input i16x8 10 23 56 15 25 29 92 45 and i16x8 12 42 58 25 55 91 192 4 values are stored as a series of 16 hex values in the v128s:

Byte index     0  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15
Hex value      0A 00 17 00 38 00 0F 00 19 00 1D 00 5C 00 2D 00

Byte index     0  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15
Hex value      0C 00 2A 00 3A 00 19 00 37 00 5B 00 C0 00 04 00

When running v128.andnot on the value, the first thing that happens is that the second input value has a bitwise NOT performed on it, meaning that each byte b becomes 0xFF - b:

Byte index     0  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15
Hex value      0C 00 2A 00 3A 00 19 00 37 00 5B 00 C0 00 04 00
Hex after NOT  F3 FF D5 FF C5 FF E6 FF C8 FF A4 FF 3F FF FB FF

A bitwise AND is then performed on input 1 and NOT input 2:

Byte index               0  1  2  3  4  5  6  7  8  9  10 11 12 13 14 15
Input 1                  0A 00 17 00 38 00 0F 00 19 00 1D 00 5C 00 2D 00
NOT input 2              F3 FF D5 FF C5 FF E6 FF C8 FF A4 FF 3F FF FB FF
Input 1 AND NOT input 2  02 00 15 00 00 00 06 00 08 00 04 00 1C 00 29 00

The resulting output v128 value is a i8x16, therefore i8x16.extract_lane_u 6 outputs the value in lane 6. This is equal to 6 (0x06), which is the equivalent of 15 (0x0F) ANDed with 230 (0xE6). 230 is the bitwise NOT of 25 (0x19).

In other words:

15 (0x0F) in binary is 0 0 0 0 1 1 1 1.
25 (0x19) in binary is 0 0 0 1 1 0 0 1.
Performing a bitwise not on the second value looks like this:
```
     0 0 0 1 1 0 0 1
NOT  1 1 1 0 0 1 1 0
```
Performing a bitwise AND on the first value and the NOT of the second value looks like this:
```
     0 0 0 0 1 1 1 1
     1 1 1 0 0 1 1 0
AND  0 0 0 0 0 1 1 0
```
0 0 0 0 0 1 1 0 is equivalent to 6.