Swap the half-byte ordering of each byte in the byte array, in place
`swap8(new Uint8Array([0x12, 0x34, 0x56, 0x78])) // becomes [0x21, 0x43, 0x65, 0x87] Copy
`swap8(new Uint8Array([0x12, 0x34, 0x56, 0x78])) // becomes [0x21, 0x43, 0x65, 0x87]
Swap the half-byte ordering of each byte in the byte array, in place