Not all octet strings need to be UTF-8

[atesgoral]

https://github.com/mcavage/node-asn1/blob/master/lib/ber/reader.js#L187

Because readString() converts the buffer to a UTF-8 string, there is an irreversible corruption, when the string is converted back to a Buffer via Buffer.from(str, 'binary').