go 1.18 fuzz tests: initial testing (#10063)

* Add basic fuzz test

* Add a few tests for HTR utils

* gofmt

* Add requirement for fuzz gotag

* Run gaz and fix tags

* Update pubsub_fuzz_test.go

I'll fix this later

Co-authored-by: prylabs-bulldozer[bot] <58059840+prylabs-bulldozer[bot]@users.noreply.github.com>

encoding/ssz/htrutils_fuzz_test.go

@@ -0,0 +1,55 @@
+//go:build fuzz && go1.18
+// +build fuzz,go1.18
+
+package ssz_test
+
+import (
+	"testing"
+
+	fssz "github.com/ferranbt/fastssz"
+	"github.com/pkg/errors"
+	"github.com/prysmaticlabs/prysm/config/params"
+	"github.com/prysmaticlabs/prysm/encoding/ssz"
+	pb "github.com/prysmaticlabs/prysm/proto/prysm/v1alpha1"
+)
+
+func FuzzUint64Root(f *testing.F) {
+	f.Fuzz(func(t *testing.T, i uint64) {
+		_ = ssz.Uint64Root(i)
+	})
+}
+
+func FuzzForkRoot(f *testing.F) {
+	frk := &pb.Fork{
+		PreviousVersion: params.BeaconConfig().GenesisForkVersion,
+		CurrentVersion:  params.BeaconConfig().AltairForkVersion,
+		Epoch:           100,
+	}
+	example, err := frk.MarshalSSZ()
+	if err != nil {
+		f.Fatal(err)
+	}
+	f.Add(example)
+
+	f.Fuzz(func(t *testing.T, b []byte) {
+		frk := &pb.Fork{}
+		if err := frk.UnmarshalSSZ(b); err != nil {
+			if errors.Is(err, fssz.ErrSize) {
+				return
+			}
+			t.Fatal(err)
+		}
+
+		if _, err := ssz.ForkRoot(frk); err != nil {
+			t.Fatal(err)
+		}
+	})
+}
+
+func FuzzPackChunks(f *testing.F) {
+	f.Fuzz(func(t *testing.T, b []byte) {
+		if _, err := ssz.PackChunks(b); err != nil {
+			t.Fatal(err)
+		}
+	})
+}