Promote Golang code to the root of the repo

- That's where the code is expected to be
- The only reason the code was buried two directories down was because
  it was originally a BOSH release
- There hasn't been a BOSH release in over two years; last one was Feb
  26, 2022
- Other than a slight adjustment to the relative location of
  `blocklist.txt` file in the integration tests, there were no other
  changes

testhelper/helpers.go

@@ -0,0 +1,38 @@
+package testhelper
+
+import (
+	"encoding/binary"
+	"math/rand"
+	"net"
+)
+
+// RandomIPv6Address is used for fuzz testing
+func RandomIPv6Address() net.IP {
+	upperHalf := make([]byte, 8)
+	lowerHalf := make([]byte, 8)
+	binary.LittleEndian.PutUint64(upperHalf, rand.Uint64())
+	binary.LittleEndian.PutUint64(lowerHalf, rand.Uint64())
+	ipv6 := net.IP(append(upperHalf, lowerHalf...))
+	// IPv6 addrs have a lot of all-zero two-byte sections
+	// So we zero-out ~50% of the sections
+	for i := 0; i < 8; i++ {
+		if rand.Int()%2 == 0 {
+			for j := 0; j < 2; j++ {
+				ipv6[i*2+j] = 0
+			}
+		}
+	}
+	// avoid pathological case: an IPv4 address []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, ?, ?, ?, ?})
+	ipv6[10] &= 0xfe
+	return ipv6
+}
+
+// Random8ByteString() returns an 8-char mixed-case string consisting solely of the letters a-z.
+func Random8ByteString() string {
+	var randomString []byte
+	for i := 0; i < 8; i++ {
+		// 65 == ascii 'A', +32 (96) == ascii 'a', there are 26 letters in the alphabet. Mix upper case, too.
+		randomString = append(randomString, byte(65+32*rand.Intn(2)+rand.Intn(26)))
+	}
+	return string(randomString)
+}