manchester encoding / decoding

manchester encoding (also known as phase encoding) is commonly used with telecommunications and data storage and would be a useful filter in CyberChef, particularly when working with SDR (software defined radio) sourced data

In short to encode, a input value of `1` becomes `01` and a input value of `0` becomes `10`

```
encode(input) {

foreach bit in input {
if bit == 0 {
output.append(1);
output.append(0);
} else {
output.append(0);
output.append(1);
}

return output;
}
```