crypto: implement rand.bytes(needed_bytes int) ?[]byte, use it consistently instead of the old rand.read(), which will change to be compatible with io and the pseudo random rand module

vlib/crypto/bcrypt/bcrypt.v

@@ -59,7 +59,7 @@ pub fn compare_hash_and_password(password []byte, hashed_password []byte) ? {
 
 // generate_salt generate a string to be treated as a salt.
 pub fn generate_salt() string {
-	randbytes := rand.read(bcrypt.salt_length) or { panic(err) }
+	randbytes := rand.bytes(bcrypt.salt_length) or { panic(err) }
 	return randbytes.bytestr()
 }